feat($http): accept function as headers value

So we can request with dynamic header value.

module.factory('Res', [
  '$resource'
  '$routeParams'
  'globalConfig'

function($resource, $routeParams, globalConfig) {
  resource('/url/:id', {id: "@id"}, {
    patch: {
      method: 'patch',
      headers: {
        'Authorization': function() {
          return "token " + globalConfig.token;
        }
      }
    }
  });
}]);
docs(angular.identity): fix missing 'angular' in identity function
fix(ngdocs): merge duplicate css class attributes
docs(ngMock): correct verifyNoOutstandingExpectation example
style(input): remove ws
docs(overview): fix typo

Removed repeated "the" in the sentence: The input invalidates itself by turning red when you enter invalid data or leave "the" the input fields blank (Line 137).
docs(contribute): improve git instructions
docs(guide/di): fix typo
docs(guide): example filter does not conditionally assign a color
docs(guide): clarify example
docs(ngList): fix example and add e2e test
test(ngList): remove disabled test

this test fails and we don't have intentions on making it pass since
we never made a commitment to implement this feature.
chore(build): add check for merge conflicts, ddescribe, and iit
fix($injector): improve $injector:nomod error message

Closes #2695
refactor(Angular.js): remove code duplication

Closes #2890
style(sanitize): fix typo in variable names
fix(scope): watches can be safely unregistered inside watch handlers

Closes #2915
feat(ngDocs): add links to source for API

 - add tests
 - the link points to the gruntUtil.getVersion().number tree on github
fix(ngValue): made ngValue to write value attribute to element
fix(ngSubmit): expose $event to ngSubmit callback