Implement `has reader` shared example.

Current spec status:
- 2.0: 338 examples, 0 failures in 0.11073 seconds.
- 2.1: 404 examples, 0 failures in 0.10687 seconds.
Implement `has writer` shared example.

Current spec status:
- 2.0: 344 examples, 0 failures in 0.10103 seconds.
- 2.1: 410 examples, 0 failures in 0.13299 seconds.
Implement `has property` shared example.

Current spec status:
- 2.0: 352 examples, 0 failures in 0.103 seconds.
- 2.1: 418 examples, 0 failures in 0.12292 seconds.
Alias property matchers as `should have …`.

Current spec status:
- 2.0: 358 examples, 0 failures in 0.12074 seconds.
- 2.1: 424 examples, 0 failures in 0.12821 seconds.
Refactor out SharedExampleGroup concern.

Current spec status:
- 2.0: 358 examples, 0 failures in 0.10372 seconds.
- 2.1: 424 examples, 0 failures in 0.12452 seconds.
Alias matcher examples as `should not pass/fail with …`.

Current spec status:
- 2.0: 364 examples, 0 failures in 0.11101 seconds.
- 2.1: 430 examples, 0 failures in 0.13562 seconds.
Merge pull request #5 from sleepingkingstudios/feature-property-examples

Implement Shared Examples for Properties