whitespace
Add clockworkd to the release package

Also documented
Update gemspec

Jeweler create gemspec.
gem dependencies in gemspec are from Gemfile.
If gemfile depends on gemspec, there is cyclic dependency.
This results in a package unable to install.

To avoid this problem, set dependencies in Gemfile.
Version bump to 0.5.0
Regenerate gemspec for version 0.5.0