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
WIP rspec 3.0 support

TODO:
Causes strange sqlite transaction error
Running with --order random gives other failures