revert: fix($compile): pass transcludeFn down to nested transclude directives

This reverts commit 113850602de2f8bc396df4ffd54bb0f1be565b17.

This change introduced regressions for several scenarios.

reduction: http://jsfiddle.net/5242N/4/
feat($interpolate): escaped interpolation expressions

This CL enables interpolation expressions to be escaped, by prefixing each character of their
start/end markers with a REVERSE SOLIDUS U+005C, and to render the escaped expression as a
regular interpolation expression.

Example:

`<span ng-init="foo='Hello'">{{foo}}, \\{\\{World!\\}\\}</span>` would be rendered as:
`<span ng-init="foo='Hello'">Hello, {{World!}}</span>`

This will also work with custom interpolation markers, for example:

     module.
       config(function($interpolateProvider) {
         $interpolateProvider.startSymbol('\\\\');
         $interpolateProvider.endSymbol('//');
       }).
       run(function($interpolate) {
         // Will alert with "hello\\bar//":
         alert($interpolate('\\\\foo//\\\\\\\\bar\\/\\/')({foo: "hello", bar: "world"}));
       });

This change effectively only changes the rendering of these escaped markers, because they are
not context-aware, and are incapable of preventing nested expressions within those escaped
markers from being evaluated.

Therefore, backends are encouraged to ensure that when escaping expressions for security
reasons, every single instance of a start or end marker have each of its characters prefixed
with a backslash (REVERSE SOLIDUS, U+005C)

Closes #5601
Closes #7517
docs($interpolate): replace `jerk` with something nicer/more neutral

I thought `jerk` illustrated the "defacing" factor nicely, but I suppose it's not very nice to have
in official documentation.
docs(*): fix its vs it's typos.

Only use the apostrophe if you can expand "it's" to "it is" and
still have a grammatical phrase.

Closes #7524