Adds spec for proxy parameter
Adds spec for proxy parameter

Checks present of --proxy command when parameter present, and it's absence when the parameter is not set

Closes #170
vicinus/puppet-python,stankevich/puppet-python,vmfarms/puppet-python,ody/puppet-python,skpy/puppet-python,skpy/puppet-python,ody/puppet-python,ghoneycutt/puppet-python,stankevich/puppet-python,ghoneycutt/puppet-python,xaque208/puppet-python,vicinus/puppet-python,vmfarms/puppet-python,xaque208/puppet-python,xaque208/puppet-python