feat(http): set custom default cache in $http.defaults.cache

When we need more control over http caching, we may want to provide
a custom cache to be used in all http requests by default.

To skip default cache, set {cache: false} in request configuration.
To use other cache, set {cache: cache} as before.

See #2079
docs($resource): Added an installation section.
fix($route): make nextRoute.$route private

the `nextRoute` object available in `$routeChangeStart` handler
accidentaly leaked  property which pointed to the route definition
currently being matched.

this was done just for the internal needs of the `$route` implementation
and was never documented as public api.

Some confusion arouse around why the $route property was not always
available on the `nextRoute` object (see #1907). The right thing for us
to do is to prefix the property with $$ for now and refactor the code
to remove the property completely in the future. Application developers
should use the `nextRoute` object itself rather than its `$route` property.
The main diff is that nextRoute inherits from the object referenced by $route.

BREAKING CHANGE: in $routeChangeStart event, nextRoute.$route property is gone.

Use the nextRoute object instead of nextRoute.$route.

Closes #1907
test($route): add tests for matching 'otherwise' routes
feat(directive): add ngKeypress directive for handling keypress event
docs(directive): minor typo fix

Changed "obeject" to "object"
docs($injector): remove extranneous 'the' from injector docs
chore($ngLocale):  Generate ngLocale files from the Closure code.
docs(ngCloak): update the CSS rule with data-ng-cloak