fix(ngTouch): remove ngClick override

[Narretz]

This commit removes the ngClick directive from the ngTouch module.
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 this feature has been removed:

• "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, 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 #13287
Closes #13558
Closes #12392
Closes #12153
Closes #11358
Closes #6432
Closes #12867
Closes #7231
Closes #13213
Closes #12082
Closes #4030
Closes #12545
Closes #6001
Closes #5307

Other issues:

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

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

BREAKING CHANGE:

The ngClick override from the ngTouch module has been removed. This means that on
touch-based devices, users might experience a 300ms delay before an ngClick event is fired.

If you rely on this behavior, consider using FastClick or
Tappy!. 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 for more info on the topic: http://developer.telerik.com/featured/300-ms-click-delay-ios-8/

[Narretz]

• add BC to migration guide after merge

Do we need any other doc changes?

[wesleycho]

This also fixes some bugs that occur with third party angular libraries due to the non-emission of the click event when using ngTouch (since the click event never really happens, but touchstart/touchend do, so the click "event" doesn't properly bubble up).

[Narretz]

We are going with deprecation of ngTouch.ngClick and disabling it by default instead: #13857