embed lua

@vanchi-zendesk check this out -- we can replace rails_req.c (106 lines) with test.lua (25 lines) -- should make it much easier to write new format matchers (thinking I'll go ahead and do nginx logs, whynot).  haven't yet taken a stab at the work-request logs. 

about 50% slower than ug_guts.c (32s vs 22s to grep through a 1gb file).

also @shajith nya nya
I suspect eof should be handled.. (Partial requests towards the end). I guess that solves one of my earlier comments about on_eof.