Fix rspec metadata integration.

#414 updated to RSpec 3.0.0.rc1 but based on the feedback we got
from that (https://github.com/rspec/rspec-core/issues/1552),
we changed the metadata a bit more
(https://github.com/rspec/rspec-core/pull/1557), which broke
things here.
Remove unnecessary require.
Merge pull request #415 from vcr/fix-for-rspec-3

Fix rspec metadata integration.