fix(ngTouch): deprecate ngClick and disable it by default

This commit deprecates the ngClick directive from the ngTouch module.
Additionally, it disables it by default. It can be enabled in the new $touchProvider with
the $touchProvider.ngClickOverrideEnabled() method.

The directive was conceived to remove the 300ms delay
for click events on mobile browsers, by sending a synthetic click event on touchstart.
It also tried to make sure that the original click event that the browser sends after 300ms
was "busted", so that no redundant "ghost-clicks" appear.

There are various reasons why the directive is being deprecated.

- "This is an ugly, terrible hack!" (says so in the source)
- It is plagued by various bugs that are hard to fix / test for all platforms (see below)
- Simply including ngTouch activates the ngClick override, which means even if you simply want
to use ngSwipe, you may break parts of your app
- There exist alternatives for removing the 300ms delay, that can be used very well with Angular:
[FastClick](https://github.com/ftlabs/fastclick), [Tappy!](https://github.com/filamentgroup/tappy/)
(There's also hammer.js for touch events / gestures)
- The 300ms delay itself is on the way out - Chrome and Firefox for Android remove the 300ms delay
when the usual `<meta name="viewport" content="width=device-width">` is set. In IE, the
`touch-action` css property can be set to `none` or `manipulation` to remove the delay. Finally,
since iOs 8, Safari doesn't delay "slow" taps anymore. There are some caveats though, which can be
found in this excellent article on which this summary is based: http://developer.telerik.com/featured/300-ms-click-delay-ios-8/

Note that this change does not affect the `ngSwipe` directive.

Issues with interactive elements (input, a etc.) when parent element has ngClick:
Closes #4030
Closes #5307
Closes #6001
Closes #6432
Closes #7231
Closes #11358
Closes #12082
Closes #12153
Closes #12392
Closes #12545
Closes #12867
Closes #13213
Closes #13558

Other issues:
- incorrect event order
- incorrect event propagation
- ghost-clicks / failing clickbusting with corner cases
- browser specific bugs
- et al.

Closes #3296
Closes #3347
Closes #3447
Closes #3999
Closes #4428
Closes #6251
Closes #6330
Closes #7134
Closes #7935
Closes #9724
Closes #9744
Closes #9872
Closes #10211
Closes #10366
Closes #10918
Closes #11197
Closes #11261
Closes #11342
Closes #11577
Closes #12150
Closes #12317
Closes #12455
Closes #12734
Closes #13122
Closes #13272
Closes #13447

BREAKING CHANGE:

The `ngClick` override directive from the `ngTouch` module is **deprecated and disabled by default**.
This means that on touch-based devices, users might now experience a 300ms delay before a click event is fired.

If you rely on this directive, you can still enable it with the `$touchProvider.ngClickOverrideEnabled()`method:

```js
angular.module('myApp').config(function($touchProvider) {
  $touchProvider.ngClickOverrideEnabled(true);
});
```

For migration, we recommend using [FastClick](https://github.com/ftlabs/fastclick).
Also note that modern browsers remove the 300ms delay under some circumstances:
- Chrome and Firefox for Android remove the 300ms delay when the well-known `<meta name="viewport" content="width=device-width">` is set
- Internet Explorer removes the delay when  `touch-action` css property is set to `none` or `manipulation`
- Since iOs 8, Safari removes the delay on so-called "slow taps"

See this [article by Telerik](http://developer.telerik.com/featured/300-ms-click-delay-ios-8/) for more info on the topic.
Note that this change does not affect the `ngSwipe` directive.