Version number changed

Bump version

Release 0.8.1-beta

Implement travis build stages

Add new integer assertion methods

* `is_positive`
* `is_negative`
* `is_greater_than`
* `is_less_than`

Add new pass, fail and error helper methods

Fix readable time output

Previously printed an incorrect value for the `ms` portion of the
running time when it is reported at the end of the test run.

Merge pull request #61 from molovo/next

v0.7.0

Release 0.7.0-alpha

Merge pull request #53 from molovo/version-0.6.x

v0.6.4