Adds support for jar files (in order to support generation of webjars - www.webjars.org); extracts duplicate code.
Fixes previous errors.
Fixes jslint warnings.
Merge branch 'master' of github.com:bertvh/grunt-maven-tasks into bertvh-master

Conflicts:
	tasks/maven_tasks.js
Merge branch 'bertvh-master'
es5 option is now set per default