build: upgraded to the minimum supported versions.

* android gradle plugin = 0.14.0
* android maven plugin = 1.2
* android build tools = 19.1.0

Also, fixed the names of the gradle plugins:
* android -> com.android.application
* android-library -> com.android.library
* android-maven -> com.github.dcendents.android-maven
build: fixed path of gradle-mvn-push.gradle.
Merge pull request #1 from e-travel/build-upgrades

Build upgrades