Merge pull request #25 from He-Ro/master

Incorporated German translation from He-Ro
Notify only main tasks
Use notification builder in compatibility library (to support Android below Jelly Bean)
Add back the Settings
Add option to change location of TeX directories
Pull all preference keys to TeXPortal
Merge branch 'master', remote-tracking branch 'upstream/master'
Updated russian translation to latest strings.xml file.
Add localization options for messages (such as no PDF viewer)
Add back languages option
Add Japanese translation.
Following upstream
Following upstream 2
Update README with localization instruction
Add simple document for testing LaTeX
Merge pull request #26 from ASMfreaK/master

Russian localization updated
Merge pull request #27 from yoneken/JapaneseTranslation

Add Japanese translation.
Externalize exception message
Add "pref" prefix to preference summary strings
Relocate preference summary messages to strings_activity_settings.xml
update japanese translation
Merge pull request #28 from yoneken/JapaneseTranslation

update japanese translation
Change the order of buttons from positive / negative to negative /
positive for honeycomb devices and later
Update German Translation