Update Japanese translations
Update Spanish translation #527
Scale down avatar images to save memory.

This gets the maximal display size of avatars from the style specification
and downsamples the loaded avatar images to be close to that size, with no
(to me) visible degradation of quality. Bonus: you actually see the rounded
corners of the images now.

Before this patch, each loaded avatar image occupied 850k of RAM, causing
the app to OOM after longer usage. With this patch, one image occupies
50k of RAM, preventing OOMs (device: Moto X).

Fixes #513
Might be a fix for #509
Add license to the top level directory.
Revise Russian translation of word 'repository'
Merge pull request #615 from fadils/master

Update Travis CI configuration for Gradle
Merge pull request #535 from Blei/less-memory-usage

Scale down avatar images to save memory.
Update README.md
Merge pull request #616 from fadils/master

Update README.md
Merge pull request #617 from 183614956/master

Revise Russian translation of word 'repository'
Merge pull request #534 from Blei/license

Add license to the top level directory.
Merge pull request #478 from crazymaster/ja

Update Japanese translations
Update Hebrew translation
Update CodeMirror to v4.8.0
Improve the source viewer in newer Android versions
Merge pull request #529 from AmauryEsparza/master

Update Spanish translation #527
Upgrade the targetSdkVersion to 21

JavascriptInterface annotations must be added to the SourceEditor for
JavaScript calls to continue working.
Merge pull request #621 from jonanp/new-sdk

Update SDK to v21
Merge pull request #622 from jonanp/improve-sourve-editor

Improve the source viewer in newer Android versions