Adds test-kitchen support.

Runs a simple chef run with percona::client and percona::server. Runs
against Ubuntu 12.04 and CentOS 6.4.
Disables test-kitchen when secure envvars unavailable.
Test only master and fetched PRs with GH flavored md issue format.
Updates with new EC2 creds as secure envvars for phlipper/chef-percona repo.
Adds gem lockfile.
Added note about platform test coverage.
Creates rake task for running test-kitchen.
Adds test-kitchen suites for backup, cluster, monitoring, and toolkit recipes.
Removes BUNDLE_GEMFILE from rake task.
Adds percona::server pre-req for xtrabackup test.
Fixes incorrect link in percona::monitoring, so test will pass.
Removes test suite for non-functional cluster recipe.
Adds deprecation notes for cluster recipe.
Adds recipe[apt] to ubuntu box run_list.
Merge pull request #65 from patcon/65-test-kitchen

Adds basic `test-kitchen` coverage.