Remove the Test::Unit tests
Provide new RSpec based tests

Also mock all the HTTP requests with VCR.
Refactor iMasquerade to use iTunes search
Update the README
Change revision since API change

[skip ci]
Drop support for Ruby 1.9.2

Add support for Ruby 2.1.x and latest Ruby.
Merge pull request #5 from RLovelett/vcr

Create newer more robust version of iMasquerade gem.

[ci skip]