Update to RSpec 3

Sorry for jumbo PR. This is sorely needed for some upcoming work.

Used transpec to update most of the files. The major exceptions are covering the changes to `pending`. Generally, I use `pending` if an `:if` was supplied, and `skip` if a filter was given or `pending` was not given a block.

\cc @opscode/client-engineers 
yeah that dropped that to force you to use "be false" or "be_falsey" -- "be_falsey" is the back-compat change.

*lots* of our "be_false" tests should probably change to "be false" to be more correct, but there's probably no good automated way to fix all of those.