Merge pull request #70 from SymmetricInfinity/safari_notification

Some additions to original Safari notification implementation
Consistently format the README
Bump to version 0.5.0
Add Ruby 2.1.0 to Travis config.  Update Rubinius dependencies by adding explicit gems, fixing label in .travis.yml
Merge pull request #71 from petergoldstein/feature/add_2_1_0

Add Ruby 2.1.0 to Travis config.  Fix Rubinius
Add Ruby 2.0 and 2.1 to list of supported Rubies
Run transpec to convert to RSpec 3.0.x syntax.  Fix two specs which were only passing because of invalid syntax.
Merge pull request #73 from petergoldstein/feature/run_transpec

RSpec 3.0.x syntax changes, fix exposed broken specs
Ignore .ruby-version
Rework badges
Add Ruby 2.1.1 to Travis
Wire up CodeClimate coverage with Travis
Remomve executables from Gem spec; we have none.
Add binstubs for RSpec.
Remove binstubs so they aren't packaged in .gem

Because we list the files to package in this Gem by shelling out to Git,
including all files that are in Git, we want to exclude our binstubs. If
we don't those binstubs get packaged with our gem, and so if you install
the gem, our binstubs end up on your PATH. OOPS!

An alternative would be to change how we list the "files" in our
.gemspec to make sure our binstubs are excluded. Maybe later...
Add specific Rubinius versions to Travis
Upgrade to RSpec 3.0.0.rc1
Add Notification#content_available? predicate

For a more consistent, Ruby-esque API.
Name the subject for Feedback Spec
Updated README to clarify notification's identifier must be an Integer.