Added compiled on date option and updated the gemspec for bundler 1.3.5

Signed-off-by: Ilya Shindyapin <ilya@shindyapin.com>
Changed the variable and added a simple rake test

Signed-off-by: Ilya Shindyapin <ilya@shindyapin.com>
Merge pull request #1 from licensetoil/uglify-options

"Compiled on" date option
Updated Bundler dependencies in gemspec