feat(docs): adding the <doc:protractor> ngdoc-tag

This is the first step in migrating tests from <doc:scenario> to <doc:protractor>.
In-documentation examples with doc:protractor sections will have their contents
output to a tab on the docs site as well as output to a standalone test file in
build/docs/ptore2e.
fix($httpBackend): Allow status code 0 from any protocol

Android 4.1 stock browser also returns status code 0 when
a template is loaded via `http` and the application is cached using
appcache.

Fixes #1356.
Closes #5547.
chore(build): add relase-after-cdn script
chore(build): check cdn before executing the release-after-cdn script
fix(docs): Clarifying versions of IE that need special fixes
fix(docs): Update reference to `$routeProvider.otherwise`
fix(docs): Add missing whitespace
feat(build): add a grunt test for running protractor tests extracted from the docs
docs(tutorial): improve experiment instructions

Closes #5697
fix($location): return '/' for root path in hashbang mode

Before this change, on the root of the application, $location.path() would return
the empty string. Following this change, it will always return a root of '/'.

Closes #5650
Closes #5712
chore(build): bugfix for script utils
test(docs): add protractor tests for docs app

Closes #5437
revert: fix($location): return '/' for root path in hashbang mode

This reverts commit 63cd873fef3207deef30c7a7ed66f4b8f647dc12.

The change breaks existing tests of Google apps. The problem is that
while we tried to avoid adding #/ to window.location.href unnecessarily
we failed doing so. Likely because by setting $path, at some point
(during a digest) we try to check if $location changed and we mistake the
default '/' with an explicit settign of the path via the `path()` method.
This results in us writing the url with '#/' into $browser.url() which updates
the window.location by adding "#/" to the url - something we tried to avoid
in the first place.

I'll reopen PR #5712.
docs($location): fix link to $locationChangeSuccess event

Closes #5717
docs(\$resource): fixed typo (s/seapph/search)

Closes #5718
docs: fix the 'view source' button for snapshots

Closes #5590
Closes #5641
fix($http): return responseText on IE8 for requests with responseType set

Closes #4464
Closes #4738
Closes #5636
feat(select): allow multiline ng-options

This patch allows the ng-options value of a <select> element to span
multiple lines, which would previously throw an error when used with filters.

Closes #5602
docs(select): update regexp grouping cheat-sheat

Update the regexp grouping comment to reflect the changes needed for
multiline expressions in ng-options for <select>.

Closes #5602
docs(changelog): release notes for 1.2.8