Bump patch version.

Merge pull request macournoyer#381 from macournoyer/bump-version

Bump version to 1.8.1

Update gemspec.

Bump version to 1.7.2 and update CHANGELOG

Bump version to 1.7.1 and update CHANGELOG

Bump version to 1.7.0 and update CHANGELOG

Update eventmachine dependency version requirements to be less strict.

Fix gemspec.

Bump version.

Downgrade Rack required version back to 1.0 to work w/ prior Rails ve…

…rsions.

Also name version 1.6.1 Death Proof.