Update fork to our dependencies

[EvanLovely]

This points the main dependencies to our forks, and alters the readme's composer create-project command to use our stuff while side-stepping Packagist (for now), and adds Travis tests.

• Go over readme to see if any download links point to upstream repo
• Add stuff to readme mentioning how we are a fork

[sghoweri]

All in all looks good on my end! Tested building and serving this branch out via:

composer create-project pattern-lab/edition-twig-standard:dev-feature/update-fork --repository '{ "type": "vcs", "url": "https://github.com/drupal-pattern-lab/edition-php-twig-standard" }' your-project-name && cd $_ && php core/console --generate

php core/console --server

As an open question to everyone before we merge though, should we:
A. Include a forked version of styleguidekit-assets-default directly here and remove the dependency from https://github.com/drupal-pattern-lab/styleguidekit-twig-default/blob/master/composer.json? (my personal recommendation)
B. Update our forked https://github.com/drupal-pattern-lab/styleguidekit-twig-default/blob/master/composer.json to point at a separate fork of styleguidekit-assets-default (which, imho, doesn't make sense as a dependency since styleguidekit-assets-default is template engine agnostic)
C. Leave it as is - which I'd recommend against given the 20 open issues and 3 open PRs...

[sghoweri]

[EvanLovely]

I think C as styleguidekit-assets-default is being actively maintained by the PL Node crew: https://github.com/pattern-lab/styleguidekit-assets-default/commits/master

We could always fork and contribute later if we saw reasons.

[EvanLovely]

OK, we've got comments on this in a couple places; but whatever: let's do it. Then it's less confusing as all pieces are our forks.