Rackspace: add keypair support
rackspace keypairs: add some Mocks
rename function 'get_key' => 'get_keypair'
rackspace: create_server - API change: options[:keypair] takes String i.s.o. Hash (-> the keypair name)
rackspace: keypairs - add unit tests
Merge branch 'rackspace' of github.com:bartvercammen/fog into rackspace

Conflicts:
	lib/fog/rackspace/mock_data.rb
	lib/fog/rackspace/requests/compute_v2/create_keypair.rb
	lib/fog/rackspace/requests/compute_v2/create_server.rb
	lib/fog/rackspace/requests/compute_v2/delete_keypair.rb
	lib/fog/rackspace/requests/compute_v2/get_keypair.rb
	lib/fog/rackspace/requests/compute_v2/list_keypairs.rb