Only enforce when it ends with _id or _type

Presently was picking up examples such as 'interest_ids' due to not checking only the end of the string.
Bump version to 0.8.1
Update matchers for RSpec 3.0

Set gemspec to use RSpec 2.99
Add `supports_block_expectations` to Reactor's supplied test matchers
Remove unnecessary `with` with no arguments

Convert specs using `transpec`
For more details: https://github.com/yujinakayama/transpec#supported-conversions