Added benchmark.js to devDeps & initial benchmarks

simple insert & update examples created
added a lot of benchmarks
benchmarks all working & output JSON

All of the benchmarks are now functioning and output the appropriate
JSON.
Fixed up command line output, now useing MONGOOSE_DEV env variable
issues from code review fixed
better mixed together calls in multi-op
added 2 new benchmarks for population
cleaned up some of the clean up code
Merge pull request #1591 from 10gen-interns/newbench

Benchmarks v0.0.1