Update installation instructions

Refs #8
more thoroughly document usage with chef 11
Merge pull request #39 from michaelglass/installation_instructions

Installation instructions
0.5.0 RELEASE
0.5.1 BUGFIX-RELEASE: added missing metadata.json inoder to make the
cookbook releaseable in community.opscode.com
second attempt at adding encryption support
fix tests
added encrypted data
chef-solo-search supports encrypted data bags
fix broken tests, more comprehensively test edge cases
remove dead code
updated documentation