Merge pull request #32 from fancyremarker/lolwut-at-sign-latest-override

Replace `latest` with much less likely to conflict `_latest_by_updated_at`
Merge pull request #33 from fancyremarker/29-caller-common-root

Add a :caller_root option to Garner::Config
Add initial benchmarking framework
Eliminate separate configuration parameters for Mongoid-specific binding strategies
No longer require all support libraries up front in spec_helper.rb