Merge pull request #600 from SamWhited/gradle

Build system and library changes (Gradle / Subtree merging)
fixed arrayoutofbounds + spelling
adjust path in render script
more error handling in xmppconnection
always use exif helper
version bump to 0.8.1
Merge pull request #605 from emdete/render_gradle_path

adjust path in render script
Fix some space/tab issues in README
Another tab fix.
Removed the last \t from the README...
Wrap "last seen" time.

Fixes #611
Merge pull request #615 from SamWhited/issue611

Wrap "last seen" time
disabled proguard. fixed gradle libs
more error handling for http connection
basic beam code / untested
Merge branch 'development' of https://github.com/siacs/Conversations into development
Merge pull request #614 from SamWhited/spacefixes

Fix some space/tab issues in README
create file explicitly before downloading image
basic beam code / untested
use different filter for nfc intents