Supermarket is live, use it for Berks source

With the Supermarket "Grand Opening"[0], we should use it as the
default source for Berksfiles.

[0]: http://www.getchef.com/blog/2014/07/03/supermarket-grand-opening/
Update the content checksums for supermarket source

The Berksfile contents cause specs to fail because the content is
different and we used the checksums generated, so they needed to be
updated.
Merge pull request #112 from opscode/jtimberman/supermarket-berks-source

Supermarket is live, use it for Berks source
Version bump and rel info for 0.2.1.
Merge pull request #143 from opscode/sersut/chef-dk-rel-info

Version bump and rel info for 0.2.1.
Make sure the context is set right while generating a template.
Update CHANGELOG with bug info.
Merge pull request #149 from opscode/sersut/gen-template-fix

Make sure the context is set right while generating a template.
Fix the version number in CHANGELOG.md.
Fixing instructions for running tests
Add validation of Policyfile.lock data structures when ingesting