Remove unnecessary Serverspec gem from Gemfile

Test Kitchen & Busser handle the installation of Serverspec on the
system to be tested; no need to have it present here.
Add ServerSpec test suites
Merge branch 'add_server_spec_tests' into integration

* add_server_spec_tests:
  Add ServerSpec test suites
  Remove unnecessary Serverspec gem from Gemfile

Conflicts:
	Gemfile
	test/integration/default/serverspec/default_spec.rb
	test/integration/default/serverspec/spec_helper.rb