Convert specs to RSpec 3.0 with Transpec

1. Ran transpec to convert the specs to RSpec 3.0.x syntax
2. Fixed a couple of RSpec deprecation warnings by changing `pending` to `skip`
3. Fixed an issue which was causing the build to fail.  Recent versions of Coveralls no longer support Ruby 1.8.7, so the Coveralls gem should only be included on 1.9+ platforms.

After these changes the build runs green for all required platforms, and it should be trivial to upgrade to RSpec 3.x.