[Gemspec] Updated dep. declarations

* Bumped ActiveSupport to a semantic dependency
* Updated gem metadata
* Fixed ActiveSupport loading in specs
[Gemspec] Fixed gemspec formatting (whitespaces)
Bumped version to 4.3.0.alpha.1 for master
[RSpec] Clean-up in spec_helper
Merge pull request #21 from arax/gemspec_update

[Gemspec] Updated dep. declarations