Extracted depur and dispatch, added CLI options and flags.

Big refactoring. Commands are now easier to construct. See
their help.

A dispatch library was added to parse all kinds of command
lines. Tests included.

Depur and posit were properly documented and styled. We're
gonna try to use tabs (for efficient heredocs) and spaces.

Tests for dispatch and extracted tests for depur.

Included a Vagrantfile with tons of machines in which these
tests currently pass.

Updated README.md with information about posit. For now, see
the help for each other tool.