enhance(componentRegistry): refactor to distinct file

Improve recovery when component id is invalid.
refactor(icon): rename icon css file.
fix(sidenav): Fix tests and typo
refactor(sidenav): adds transition for `md-locked-open` changes

Closes #789.
refactor(sidenav): fixes animation issue in previous commit
fix(radioButton): arrowkey navigation with disabled buttons

Closes #1040.
update(build): build-demo no longer requires prefixes

'material.component.' prefixes are no longer required with 'gulp build-demo -m slider'
update(utils): refactor iterator

Uses angular.config() to decorate and inject iterator into $mdUtils
Also update iterator::previous() to use limit parameter
docs(guides): promote `gulp validate` over `gulp karma`