initial pass at getting cacher-ng to cleanly separate from cacher-client
[COOK-2859] prevent forced run of cacher-client recipe

Merged Derrick Bryant's patch and updated to force node['apt']['compiletime']
to false if node['apt']['caching_server'] is true. This will prevent use of
compiletime with apt::cacher-ng in the run list.
make safe for testing with Debian
Greatly expand testing coverage.

Added Debian 7.1 and Ubuntu 13.04 as platforms for test-kitchen. Added
cacher-client and cacher-ng with client suites of tests. Also added basic
ChefSpec tests.
updated testing documentation
Merge branch 'COOK-3426'