new function to execute the Jenkins CLI
cleanup
move the jenkins-cli.jar out of 'lib' to 'java_deps', add unit test for #exec_cli
use mixlib-shellout instead of popen to 1) return user readable output; 2) handle the errors
Merge branch 'patch_cli' of https://github.com/missedone/jenkins_api_client

Conflicts:
	.travis.yml
	Gemfile
	spec/unit_tests/client_spec.rb