Bitly links now support HTTPS - Yay!

Both invite links now work over `https` -- yes I tested  :-)
More info:

https://github.com/EFForg/https-everywhere/pull/4505
http://webmasters.stackexchange.com/questions/87163/do-bitly-branded-short-domains-support-https/92407#92407

PS: https://sgnl.link/1IvurmD also works.

Closes #5460
Fixes #4060

// FREEBIE

src/org/thoughtcrime/securesms/ConversationActivity.java

@@ -527,8 +527,8 @@ public class ConversationActivity extends PassphraseRequiredActionBarActivity
   private void handleInviteLink() {
     try {
       boolean a = SecureRandom.getInstance("SHA1PRNG").nextBoolean();
-      if (a) composeText.appendInvite(getString(R.string.ConversationActivity_lets_switch_to_signal, "http://sgnl.link/1LoIMUl"));
-      else   composeText.appendInvite(getString(R.string.ConversationActivity_lets_use_this_to_chat, "http://sgnl.link/1MF56H1"));
+      if (a) composeText.appendInvite(getString(R.string.ConversationActivity_lets_switch_to_signal, "https://sgnl.link/1LoIMUl"));
+      else   composeText.appendInvite(getString(R.string.ConversationActivity_lets_use_this_to_chat, "https://sgnl.link/1MF56H1"));
     } catch (NoSuchAlgorithmException e) {
       throw new AssertionError(e);
     }