Add performance testing to the testing suite

[KrisSiegel]

Since msngr.js is meant to run as quickly and lean as possible, it's vitally important that its performance be measured, tuned, and measured again in every single release. Several versions ago benchmark.js was integrated but it was incredibly clunky and didn't work consistently.

This issue is for investigating adding a performance test suite that is run against all pull requests that allows the measure and improvement of msngr.js's performance.

• Investigate adding a similar to unit testing capability where each component of msngr.js is performance tested. Benchmark.js might still be a good candidate for this.
• Revise testing process to include running benchmarks in travis to ensure builds fail if they are too slow (this is a bit subjective, will need some investigation to figure this one out). Might need Modernize the build system #72 to finish first.