Add a simple module for measuring performance.
Add a simple module for measuring performance.

I tried to write blocks of code that are representative of how I use lua_sandbox
in production. This isn't intended to produce numbers that are meaningful in
isolation. Rather, this is only only so that performance changes can be
meaningfully compared before and after

An example run:

    capsule_test 18.6332478523
    re_test 23.189412117
    simple_test 15.8587939739

ketralnis/lua_sandbox,ketralnis/lua_sandbox,ketralnis/lua_sandbox