Update rakefile

Remove gem bundling in rake and updated the rakefile to default task to
rspec testing.
Added user collection method and JSON support

Added the ability to query a given user’s master collection. In order
to support this, basic JSON parsing to objects was added via the Hashie
gem.
Bump version number of 1.2.0

Adding functionality for getting user collection bumps the version
number per semver.org guidelines
Basic .get_user_collection test

First test using JSON payload for user collection.
More tests for get_user_collection

Added another attribute test and a bogus attribute check.
Merge pull request #23 from bradykimball/master

1.2 Release: Merge in baseline JSON support via get_user_collection method