Update to RSpec 3

Conversion involved the following steps:
- Use transitional RSpec version 2.99
- Convert specs to RSpec 2.99.1 syntax with Transpec
- Simplify converted specs that used to use 'its'
- Update dependency to RSpec 3.0
- Remove rcov options from rake tasks
- Remove deprecated RSpec config option from spec_helper
- Use current matcher protocol for smell matchers
- Update matchers used in step definitions
- Improve some expectations by using operator matchers