[sample] Added possiblity to run samples on pre-L release
[build] Fixed according to 13.3 plugin update

Closes: Changed tools:node to tools:overrideLibrary according
to change in android gradle plugin.
http://tools.android.com/tech-docs/new-build-system
Update README.md
[core] Fix TwoWayLayoutManager's LOGTAG
[core, layouts] Remove unnecessary argument from constructors
Merge pull request #115 from jacek-marchwicki/feature-pre-l-release
[core] Fix potential null pointer in TwoWayLayoutManager
[layouts] Fix potential null pointer in BaseLayoutManager
Merge pull request #109 from athornz/master
[release] Add CHANGELOG file
[readme] Update stable release version
[build] Updated to android Lollipop
Merge pull request #125 from jacek-marchwicki/fix-android-lollipop
[build] Added travistCI
Merge pull request #127 from jacek-marchwicki/travis-integration2
Merge branch master