Setup gradle build

Add `license` plugin and apply ASL 2.0 to all sources
Add `publishing` and i`bintray` plugins with custom pom settings
Add `cobertura` and `coveralls` plugins
Merge branch 'build_setup_update' of https://github.com/aalmiray/gvm-sdk into aalmiray-build_setup_update

Conflicts:
	LICENSE
	build.gradle
Minor code formatting.