Remove `superagent` dependency

We’ve replaced it with more modern and Node.js based `got`:
https://www.npmjs.com/package/got

package.json

@@ -71,7 +71,6 @@
     "rimraf": "^2.6.2",
     "semver": "^5.4.1",
     "spellchecker": "^3.4.4",
-    "superagent": "^3.8.2",
     "testcheck": "^1.0.0-rc.2",
     "websocket": "^1.0.25"
   },

yarn.lock

@@ -916,10 +916,6 @@ compare-version@^0.1.2:
   version "0.1.2"
   resolved "https://registry.yarnpkg.com/compare-version/-/compare-version-0.1.2.tgz#0162ec2d9351f5ddd59a9202cba935366a725080"
 
-component-emitter@^1.2.0:
-  version "1.2.1"
-  resolved "https://registry.yarnpkg.com/component-emitter/-/component-emitter-1.2.1.tgz#137918d6d78283f7df7a6b7c5a63e140e69425e6"
-
 compress-commons@^1.2.0:
   version "1.2.2"
   resolved "https://registry.yarnpkg.com/compress-commons/-/compress-commons-1.2.2.tgz#524a9f10903f3a813389b0225d27c48bb751890f"
@@ -998,10 +994,6 @@ convert-source-map@^1.3.0:
   version "1.5.1"
   resolved "https://registry.yarnpkg.com/convert-source-map/-/convert-source-map-1.5.1.tgz#b8278097b9bc229365de5c62cf5fcaed8b5599e5"
 
-cookiejar@^2.1.0:
-  version "2.1.1"
-  resolved "https://registry.yarnpkg.com/cookiejar/-/cookiejar-2.1.1.tgz#41ad57b1b555951ec171412a81942b1e8200d34a"
-
 core-js@^2.4.0:
   version "2.4.1"
   resolved "https://registry.yarnpkg.com/core-js/-/core-js-2.4.1.tgz#4de911e667b0eae9124e34254b53aea6fc618d3e"
@@ -1827,7 +1819,7 @@ expand-range@^1.8.1:
   dependencies:
     fill-range "^2.1.0"
 
-extend@3, extend@^3.0.0, extend@~3.0.1:
+extend@3, extend@~3.0.1:
   version "3.0.1"
   resolved "https://registry.yarnpkg.com/extend/-/extend-3.0.1.tgz#a755ea7bc1adfcc5a31ce7e762dbaadc5e636444"
 
@@ -2039,9 +2031,6 @@ from2@^2.1.1:
   dependencies:
     inherits "^2.0.1"
     readable-stream "^2.0.0"
-formidable@^1.1.1:
-  version "1.1.1"
-  resolved "https://registry.yarnpkg.com/formidable/-/formidable-1.1.1.tgz#96b8886f7c3c3508b932d6bd70c4d3a88f35f1a9"
 
 fs-extra-p@^4.5.0:
   version "4.5.0"
@@ -3496,10 +3485,6 @@ merge-source-map@^1.0.2:
   dependencies:
     source-map "^0.6.1"
 
-methods@^1.1.1:
-  version "1.1.2"
-  resolved "https://registry.yarnpkg.com/methods/-/methods-1.1.2.tgz#5529a4d67654134edcc5266656835b0f851afcee"
-
 micromatch@^2.3.11:
   version "2.3.11"
   resolved "https://registry.yarnpkg.com/micromatch/-/micromatch-2.3.11.tgz#86677c97d1720b363431d04d0d15293bd38c1565"
@@ -3542,10 +3527,6 @@ mime@^1.3.4:
   version "1.4.0"
   resolved "https://registry.yarnpkg.com/mime/-/mime-1.4.0.tgz#69e9e0db51d44f2a3b56e48b7817d7d137f1a343"
 
-mime@^1.4.1:
-  version "1.6.0"
-  resolved "https://registry.yarnpkg.com/mime/-/mime-1.6.0.tgz#32cd9e5c64553bd58d19a568af452acff04981b1"
-
 mime@^2.2.0:
   version "2.2.0"
   resolved "https://registry.yarnpkg.com/mime/-/mime-2.2.0.tgz#161e541965551d3b549fa1114391e3a3d55b923b"
@@ -4309,10 +4290,6 @@ qs@5.2.0:
   version "5.2.0"
   resolved "https://registry.yarnpkg.com/qs/-/qs-5.2.0.tgz#a9f31142af468cb72b25b30136ba2456834916be"
 
-qs@^6.5.1, qs@~6.5.1:
-  version "6.5.1"
-  resolved "https://registry.yarnpkg.com/qs/-/qs-6.5.1.tgz#349cdf6eef89ec45c12d7d5eb3fc0c870343a6d8"
-
 qs@~5.1.0:
   version "5.1.0"
   resolved "https://registry.yarnpkg.com/qs/-/qs-5.1.0.tgz#4d932e5c7ea411cca76a312d39a606200fd50cd9"
@@ -4321,6 +4298,10 @@ qs@~6.4.0:
   version "6.4.0"
   resolved "https://registry.yarnpkg.com/qs/-/qs-6.4.0.tgz#13e26d28ad6b0ffaa91312cd3bf708ed351e7233"
 
+qs@~6.5.1:
+  version "6.5.1"
+  resolved "https://registry.yarnpkg.com/qs/-/qs-6.5.1.tgz#349cdf6eef89ec45c12d7d5eb3fc0c870343a6d8"
+
 query-string@^5.0.1:
   version "5.1.0"
   resolved "https://registry.yarnpkg.com/query-string/-/query-string-5.1.0.tgz#9583b15fd1307f899e973ed418886426a9976469"
@@ -5107,21 +5088,6 @@ sumchecker@^2.0.1, sumchecker@^2.0.2:
   dependencies:
     debug "^2.2.0"
 
-superagent@^3.8.2:
-  version "3.8.2"
-  resolved "https://registry.yarnpkg.com/superagent/-/superagent-3.8.2.tgz#e4a11b9d047f7d3efeb3bbe536d9ec0021d16403"
-  dependencies:
-    component-emitter "^1.2.0"
-    cookiejar "^2.1.0"
-    debug "^3.1.0"
-    extend "^3.0.0"
-    form-data "^2.3.1"
-    formidable "^1.1.1"
-    methods "^1.1.1"
-    mime "^1.4.1"
-    qs "^6.5.1"
-    readable-stream "^2.0.5"
-
 supports-color@4.4.0, supports-color@^4.0.0:
   version "4.4.0"
   resolved "https://registry.yarnpkg.com/supports-color/-/supports-color-4.4.0.tgz#883f7ddabc165142b2a61427f3352ded195d1a3e"