Add benchmark test suite

[esamattis]

Sending this mainly as a starting point for discussion on how and what should be benchmarked in Redux & react-redux.

Few points to begin with:

• The production builds should be used for benchmarking
• It should not be required to open devtools when running the bench

[gaearon]

Wow, thank you! It's a great start.

[timdorr]

@epeli I know it's been a while, but any progress on this?

[esamattis]

Unfortunately no. Better close this for now.