Add rspec config file

* Colorize output
* Run tests in random order
* Profile 5 (default of 10 is too noisy)
Don't cache CtrlP results when using ag

It gets very annoying to manually force CtrlP to re-index every time I
add a new file. Since ag is so fast, we can turn off caching when it
powers CtrlP without any noticeable impact on search speed.
Merge remote-tracking branch 'upstream/master'