feat(benchmark): add a simple benchmark for the di module

It adds the following tasks to the gulpfile:

1. `benchmarks/clean` // removes the compiled files
2. `benchmarks/build` // compiles all the files in `benchmarks` and creates a benchpress build
3. `benchmarks/run` // fires up a server

It also includes a very simple benchmark. It is not very useful and just serves as an example.

Extra notes:
1. Benchmarks run against the build folder. Right now everything is compiled with type checks enabled. We need to have another task (or maybe a flag) that compiles everything in production mode (without type checks).
Could you also transpile the benchmarks into dart, although we don't have a runner for Dart yet? Via that we make sure that the benchmarks don't use things that are not possible in Dart...
So just add a `benchmarksDart` as well...