Change DateUtils string 'Now' to 'Just now'

Changes the DateUtils string 'Now' to 'Just now' which is a better fit
imho.
Used for messages in the conversation view that e. g. just have been
received.

// FREEBIE

Closes #5761

res/values/strings.xml

@@ -222,7 +222,7 @@
     <string name="CustomDefaultPreference_none">None</string>
 
     <!-- DateUtils -->
-    <string name="DateUtils_now">Now</string>
+    <string name="DateUtils_just_now">Just now</string>
     <string name="DateUtils_minutes_ago">%d min</string>
 
     <!-- DeviceListActivity -->

src/org/thoughtcrime/securesms/util/DateUtils.java

@@ -48,7 +48,7 @@ public class DateUtils extends android.text.format.DateUtils {
 
   public static String getBriefRelativeTimeSpanString(final Context c, final Locale locale, final long timestamp) {
     if (isWithin(timestamp, 1, TimeUnit.MINUTES)) {
-      return c.getString(R.string.DateUtils_now);
+      return c.getString(R.string.DateUtils_just_now);
     } else if (isWithin(timestamp, 1, TimeUnit.HOURS)) {
       int mins = convertDelta(timestamp, TimeUnit.MINUTES);
       return c.getResources().getString(R.string.DateUtils_minutes_ago, mins);
@@ -66,7 +66,7 @@ public class DateUtils extends android.text.format.DateUtils {
 
   public static String getExtendedRelativeTimeSpanString(final Context c, final Locale locale, final long timestamp) {
     if (isWithin(timestamp, 1, TimeUnit.MINUTES)) {
-      return c.getString(R.string.DateUtils_now);
+      return c.getString(R.string.DateUtils_just_now);
     } else if (isWithin(timestamp, 1, TimeUnit.HOURS)) {
       int mins = (int)TimeUnit.MINUTES.convert(System.currentTimeMillis() - timestamp, TimeUnit.MILLISECONDS);
       return c.getResources().getString(R.string.DateUtils_minutes_ago, mins);