docs(guide): remove redundancy in providers guide

Highlighted the Best Practices section, and took the styling from the Services doc.
Also removed some superfluous wording that was in the "Provider Recipe"
docs(tutorial): remove index.html from app url
docs(guide/concepts): update example

The "A first example: Data binding" section it implies that the `required` directive is
doing something, but it isn't.

I just removed the parts the refer to the required directive to avoid confusion.
fix(ngHref): remove attribute when empty value instead of ignoring

Closes #2755
docs($resource): note methods list is non-exhaustive

The existing documentation for custom action methods implies that only a small
list of upper case methods can be used for custom $resource actions.
perf($parse): don't use reflective calls in generated functions

Chrome and FF are smart enough to notice that the key is is a string literal, so this change doesn't
make a difference there. Safari gets a boost. I haven't tested IE, but it can't cause harm there. :)

http://jsperf.com/fn-dereferencing
feat($q): add streamlined ES6-style interface for using $q

This potentially helps lead the way towards a more performant fly-weight implementation, as discussed
earlier in the year. Using a constructor means we can put things in the prototype chain, and essentially
treat $q as a Promise class, and reuse methods as appropriate.

Short of that, I feel this style is slightly more convenient and streamlined, compared with the older
API.

Closes #8311
Closes #6427 (I know it's not really the solution asked for in #6427, sorry!)
fix(jqLite): triggerHandler support unbind self

Fixes .one if the event is invoked from triggerHandler.

Closes #5984
fix(docs): change plnkr form to open in same window

Form previously posted to target="_blank", but pop-up blockers were causing this to not work.
If a user chose to bypass pop-up blocker one time and click the link, they would arrive at
a new default plnkr, not a plnkr with the desired template.

This fix removes the _blank target, causing the plnkr to open in the current window/tab.
feat($compile): change directive's restrict setting to default to EA (element/attribute)

Previously we defaulted just to A because of IE8 which had a hard time with applying css styles to HTMLUnknownElements.

This is no longer the case with IE9, so we should make restrict default to EA. Doing so will make it easier to create
components and avoid matching errors when creating new directives

BREAKING CHANGE: directives now match elements by default unless specific restriction rules are set via `restrict` property.

This means that if a directive 'myFoo' previously didn't specify matching restrictrion, it will now match both the attribute
and element form.

Before:

 <div my-foo></div> <---- my-foo attribute matched the directive
 <my-foo></my-foo>  <---- no match

After:

 <div my-foo></div> <---- my-foo attribute matched the directive
 <my-foo></my-foo>  <---- my-foo element matched the directive

It is not expected that this will be a problem in practice because of widespread use of prefixes that make "<my-foo>" like
elements unlikely.

Closes #8321