Extract ReviewRunner from Engine for easier testing

Change-Id: Ic8b1ea61285f6c8dfe07d1695524bcee98e70e79
JSHint support added.
update release link
checkstyle and findbugs tests
Merge pull request #50 from damianszczepanik/launch-with-gradle

Launch with gradle
Merge pull request #51 from gildur/jshint

JSHint support added.
TestEnvironment introduced + refactor
codecov
jacoco + codecov
shields + codecov
merge
Merge pull request #55 from TouK/inc_coverage

Test refactor
now you can run gradle.build also if this file is not in project root directory