drop mock dependency

mock is not used anywhere in the module, let's drop it.
This patch will help to hit this bug:
https://launchpad.net/bugs/1492636

Change-Id: Id8a2ab10329c05af5b766e2a441a744ced073671

config_defaults.yml

@@ -16,7 +16,6 @@ Gemfile:
       - gem: puppet-lint-variable_contains_upcase
       - gem: puppet-lint-numericvariable
       - gem: json
-      - gem: webmock
       - gem: 'puppet-openstack_spec_helper'
         git: 'https://git.openstack.org/openstack/puppet-openstack_spec_helper'
     ':system_tests':

moduleroot/spec/spec_helper.rb

@@ -1,6 +1,5 @@
 require 'puppetlabs_spec_helper/module_spec_helper'
 require 'shared_examples'
-require 'webmock/rspec'
 
 require 'puppet-openstack_spec_helper/defaults'
 require 'rspec-puppet-facts'