style($templateCache): remove trailing whitespace

This was introduced by 2ca6d650e8a13cee28f11c38622cab231787325f, somewhat inexplicably as I had run
grunt ci-checks locally. But regardless, this should fix this up.
chore(package.json): update dgeni-packages dependency
docs(guide/concepts): move ng-app into example text

Closes #6639
chore(version-info): previousVersions should not return `undefined`

Closes #6702
chore(utils): fix version number processing

The changes to version-info meant that the version being injected into
the code at build time was missing the "dot" (patch) version and the
release code-name.
fix(angular.bootstrap): only allow angular to load once

This is hard to test as a unit-test, since it involves the actual loading
of angular, but it turns out that it is easy to test using a protractor
e2e test.

Closes #5863
Closes #5587
chore(log): add `log.empty()`  method to the testing logger

`log.empty()` is the same as `log.reset()`, except thati `empty()`  also returns the current array with messages

instead of:

```
// do work
expect(log).toEqual(['bar']);
log.reset();
```

do:

```
// do work
expect(log.empty()).toEqual(['bar']);
```
fix(Scope): $watchCollection should call listener with oldValue

Originally we destroyed the oldValue by incrementaly copying over portions of the newValue
into the oldValue during dirty-checking, this resulted in oldValue to be equal to newValue
by the time we called the watchCollection listener.

The fix creates a copy of the newValue each time a change is detected and then uses that
copy *the next time* a change is detected.

To make `$watchCollection` behave the same way as `$watch`, during the first iteration
the listener is called with newValue and oldValue being identical.

Since many of the corner-cases are already covered by existing tests, I refactored the
test logging to include oldValue and made the tests more readable.

Closes #2621
Closes #5661
Closes #5688
Closes #6736
feat($compile): add support for $observer deregistration

In order to make the behavior compatible with $rootScope.$watch and $rootScope.$on methods, and
make it possible to deregister an attribute observer, Attributes.$observe method now returns a
deregistration function instead of the observer itself.

BREAKING CHANGE: calling attr.$observe no longer returns the observer function, but a
    deregistration function instead.

    To migrate the code follow the example below:

    Before:

```
    directive('directiveName', function() {
      return {
        link: function(scope, elm, attr) {
          var observer = attr.$observe('someAttr', function(value) {
            console.log(value);
          });
        }
      };
    });
```

    After:

```
    directive('directiveName', function() {
      return {
        link: function(scope, elm, attr) {
          var observer = function(value) {
            console.log(value);
          };

          attr.$observe('someAttr', observer);
        }
      };
    });
```

Closes #5609
feat(ngMock.$httpBackend): added support for function as URL matcher

It's now possible to pass a function to match the URL in $httpBackend mocked
expectations. This gives a more sophisticate control over the URL matching
without requiring complex RegExp mantainance or the workaround of creating
an object with a `test` function in order to mimic RegExp interface.

This approach was suggested in [this
thread](https://groups.google.com/d/msg/angular/3QsCUEvvxlM/Q4C4ZIqNIuEJ)

Closes #4580
style(ngMocks): remove ws
docs(tutorial/step_05): removed stray "a"
docs(tutorial/step_05): fix services link