Search for karma values via regex

[pharaun]

Should be somewhat straight forward to have regex searches over the karma values.

However there's a few attack vectors to be aware of such as:

1. exponential backtracking regex
2. cpu/memory leaks
3. fact that the backing store is an sqlite database means we'll need to bring the values in memory for searching.

[pharaun]

https://code.google.com/p/re2/ is one such regex engine that we could use.