remove traceur runtime requirement

[jeffbcross]

As discussed in #21, it's problematic for benchpress runtime libraries to add $traceurRuntime and System to the window, as code under test may be using a conflicting version of Traceur. In the case of benchpress, the dependency injection library requires the traceur runtime to be added.

Proposed fix: write a lightweight DI implementation with subset of the angular/di.js API, that will ship with the bp.js runtime, but continue to use the real di.js for testing since it has nice mock utilities.