Externalize extensions, polishing

[guybedford]

This externalizes the Chomp template extensions into a separate repo - https://github.com/guybedford/chomp-extensions.

The template extensions are now loaded from JSPM via https://ga.jspm.io/npm:@chompbuild/templates@0.1.3/npm.js etc.

Remote extensions are then cached locally for fast task runs.

This PR also includes a number of other improvements:

• ANSI colours
• Fixes an issue where interpolates wouldn't build their direct files anymore (tasks always had to be run by name)
• Args support in commands (see below)
• Fix a bug where chomp --format would eject the templates as well incorrectly

Args support in commands

chomp echo -- "hello world"
> hello world

defined by:

version = 0.1

[[task]]
name = 'echo'
args = ['MESSAGE']
run = 'echo $MESSAGE'