I merged gouthamvel's repository (https://github.com/gouthamvel/gracenote), and wrote rspec tests.

and write rspec tests of all Gracenote class's instance methods.

This commit includes these commits.

fixes http error caused with ssl

cleans up and add new artist_image feature

removes cover causing multi image resp

Add test of Gracenote.initialize

Add test of Gracenote#basic_track_search

Add test of Gracenote#artist_image

edit README