Updating run loop documentation

Backburner was updated and the documentation for
throttle/debounce/cancel needs to be updated to reflect
new functionality
Remove `RSVP.Promise#fail` in favor of `catch`.


After discussion with @wycats and @domenic, it was decided we should remove
`fail` before it enters an official release

- es3 users should use the ['catch'] syntax
- plans are to add a transpiler for people to es5 -> es3 (for finally and catch) etc.
[NICETHING beta] Name anon LinkView CPs

This gets rid of lots of (anonymous function)s i've
been running into lately in the call stack.
Merge pull request #3902 from stefanpenner/remove-promise-fail

Remove `RSVP.Promise#fail` in favor of `catch`.
Merge pull request #3904 from machty/linkview-cp-names

[NICETHING beta] Name anon LinkView CPs
Merge pull request #3889 from kingpin2k/update_backburner_functionality

Updating run loop documentation
[BUGFIX beta] Use a bundler cache to speed builds.
Merge pull request #3907 from rjackson/use_cache

[BUGFIX beta] Use a bundler cache to speed builds.