Adding front end assets to composer.json.

[grasmash]

Currently, simply using composer to install lightning will not build the front end dependencies. Drush make must be used, or npm install must be called from the lightning directory. This causes automated tests to fail.

This PR uses composer to manage front end dependencies.

[grasmash]

A few notes:

• This PR relies on Prevent fatal str_pos() error in dist parsing. fxpio/composer-asset-plugin#216 being merged upstream
• This notably slows down composer builds, at least on the first run. This is due to npm package information being downloaded. It is cached and subsequent builds are faster.
• We do not have a mechanism to ignore recursive dependencies, such as jquery, jqueryui, and backbone.
• I believe this allows us to remove code. Namely the bower.json file, possibly package.json, and a few Phing targets.

[grasmash]

fxpio/composer-asset-plugin#216 has been merged upstream. @balsama Can you restart travis tests and see if we get a pass?

[balsama]

@grasmash errored: https://travis-ci.org/acquia/lightning/builds/125854511#L512

[grasmash]

One more time? :p

[balsama]

@grasmash Same result: https://travis-ci.org/acquia/lightning/builds/125854511

[grasmash]

Very strange, it's claiming that the underscore package being downloaded is corrupt. Download the same package locally for me is fine. Not sure what would cause that.

[grasmash]

fxpio/composer-asset-plugin#100

[balsama]

hmmm. and PR #119 doesn't have a cache on travis - presumably because it never finished?

[danepowell]

See #129 and #131