Remove engine, parser, and Makefile.

## Overview

This pull request removes:

1. The `engine` package.
2. The `parser` package.
3. `Makefile` & `configure`
4. `Gemfile` & `Gemfile.lock`

Since we are rewriting those two packages I thought it'd be best to have a clean slate. We can reference the old code using the `0.8.6` tag in git anyway. Since we're going the pure Go route, we can also get rid of the Makefile. Let me know if there are "release" make targets that need to be kept but most everything I saw in there was related to parser or data store libraries.

I removed the Gemfiles because every time Ruby configuration is added to a Go project Rob Pike sheds a tear.

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/cc @pauldix @toddboom @otoolep