Upgrade to CodeMirror 2.3.5

Close #268
Add script tag for overlay.js needed by gfm mode
Add dependency to markdown mode
Add missing strings

Closes #267
Update spanish translation

* Add new strings.
* Use infinitive instead of imperative for strings indicating actions.
* Reorder some strings. This way it's easier to check for unstranslated and unused strings line by line.

Closes #269
Remove unused util scripts
Add initial .travis.yml file
Upgrade target to android-16
Remove custom script
Upgrade test target version to 16
Upgrade sdk platform version to 16
Upgrade target to 16 in default properties file at root
Upgrade travis to latest Android SDK
Correct typos in POM name elements
Update imports to fix problems with ADT v.21

Closes #273
Update imports to use R classes from app package
Put local Android paths first
Log SDK install options
Install 4th SDK option
Install 1st SDK option