chore(ngdocs): replace showdown.js with marked.js
feat(ngMock): support delay limit for $timeout.flush
feat(ngMock): $timeout.flushNext can expect specific timeout delays

the $timeout mock's flush method allows flushing queued up requests
but doesn't allow to for checking with what delay a task was queued
up. flushNext flushes the next queued up task and can asserts the
scheduled delay.
chore($compile): removed unused variable
fix(grunt): change css wrapping to prepend styles to the top of the head tag

angular.css is used by the utils.js CSS wrap operation, but ng-hide or
any other CSS styles present in angular.css cannot be overridden unless
the styles appear before the stylesheet is in place. This fix allows
for this to work