fix($compile): don't check attr.specified on non-ie7

the specified attribute is depricated and creates warnings in Firefox

Closes #3231
Closes #2160
feat(ngMobile): emit 'swipeleft' and 'swiperight' events

Similar to ngMobile clicks, these events were not capturable by other
directives. Now they emit 'swipeleft' and 'swiperight' events that can
be follow with element.on('swipeleft', ...).
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
fix($compile): don't use new with minErr

Someone wrote `throw new $compileMinErr(...)` when it should have been
`throw $compileMinErr(...)`. This caused a build warning.