WIP Megacommit - faster parser

```
ruby bench.rb
                           user     system      total        real
parslet                2.260000   0.000000   2.260000 (  2.258811)
hand                   0.060000   0.000000   0.060000 (  0.059822)
regexp                 0.020000   0.000000   0.020000 (  0.023754)
```
Fixes the unescape in the regexp parser
Introduces a Logfmt::Generator module to serialize ruby objects into logfmt

Usage:

    require 'logfmt/generator'
    Logfmt.generate(obj)