fix(ngEventDirectives): parse expression only once during compile phase.
docs($location): update paramValue description for search()

search() supports an array for paramValue, but this is not described in the docs.
docs($parse): Fix typo
docs(guide/contribute): remove redundancy and link to CONTRIBUTING.md
style: remove ws
fix(ngIf): destroy child scope when destroying DOM
fix(ngModel): deregister from the form on scope not DOM destruction

Due to animations, DOM might get destroyed much later than scope and so the element $destroy event
might get fired outside of $digest, which causes changes to the validation model go unobserved
until the next digest. By deregistering on scope  event, the deregistration always happens
in $digest and the form validation model changes will be observed.

Closes #4226
Closes #4779
chore(docs): fix ordering of docs in the guide
docs($log): add the word "safely" to clarify

I was reading the doc and had to read the code to be sure it was safe.  Spelling it out seems easier.

Closes #4760
docs(overview): improve readability

Inserted a couple of line breaks to increase readability.

Closes #4756
docs(guide/understanding-controllers): fix typo in example

Broken - $scope.spicy = 'very';
Works - $scope.spice = 'very';

Closes #4752
docs($http): note that default $http headers can be overridden

Closes #4750
docs(input): fix typo

Closes #4734
docs(guide): add SEO4Ajax to the SEO tools list

Closes #4748
docs(guide/directive): fix transclusion example

The example about transclusion and scopes worked only because the order of `scope` and `element`
arguments is wrong, which means that the `name' property of the scope is not really being updated.
To really work, the directive has to define its own scope, either a new child scope or, as is more
common with transclusion, an isolated scope.

Closes #4774
fix(ngdocs): `shortDescription()` should not error if no `description`
fix(ngdocs): create mock Doc objects correctly
chore(grunt): add test:docsgen to ci checks
chore(ngAnimate): ensure elapsedTime values are in seconds and millseconds
chore($sniffer): make msie variable public

The msie variable is a global variable used within the ng core which contains the
version number for the current Internet Explorer browser that is rendering the
application. Other modules outside of the ng core could make use of this variable
instead of having to rollout duplicate detection code. This code makes it easy to
reuse this simple property within the $sniffer service.