[FIX] always run view callbacks on ui thread

Merge branch 'new/offline-sending' of github.com:RocketChat/Rocket.Chat.Android into new/offline-sending

fragment and view

Remove retryIO when sending messages letting the JobScheduler to do this job and always keep the send button enabled since we are now offline

[FIX] Build instruction for develop-2.x branch

[NEW] Add listen to updates on own profile.

[NEW] Feature/attachment fields

[FIX] Avatar URL for channels and groups.

[CHORE] Increment version of the app to Beta 6

[IMPROVEMENT] Added ripple effect for user status

[FIX] Remove the check for internet connection.

[FIX] Small pack of fixes on Uri.kt and permissions

Change statusChannelList to CopyOnWriteArrayList in order to better keep track of concurrent modifications

When file extension is empty set the mime-type to be application/octet-stream - arbitrary binary data