Add metrics package and start keeping a few basic metrics in the proxy.
Use make deps to get dependencies.
Fix tests to include upstream metrics
Merge pull request #28 from pquerna/add_proxy_metrics

Add Metrics
Add -cpuprofile option.
Use a pool for Otto instances, and for code loading only load if the file size/mtime changes.
If GOMAXPROCS is not set, set it to the number of CPUs.
Let vulcan pick GOMAXPROCS itself by default.
Merge pull request #38 from pquerna/cpu_profiling_improvements

(RFR) Profiling Improvements