Fix the Doc tasks, remove some rails 2.3 support leftovers, fix some rspec deprecations, and update some docs.

Hey Guys,

I did this work last night because I thought I was going to have to maintain a fork of sunspot. Thank goodness that isn't the case. :+1: Here's what I did:

* Fixed rspec deprecations by switching from `mock` -> `double` for constructing test doubles.
* Pull in #376 to properly declare the dependencies of our files, rather than relying on requires external to the library
* Remove Hanna and fix the doc tasks in sunspot and sunspot_rails
* Remove sunspot_rails/lib/sunspot/rails/init.rb, which was left over from the rails 2.3 support
* Pull in #439 and #375, so that `StubSessionProxy` would better reflect the features of the ordinary session object.
* Solved the `PostWithDefaultScope` rails 4 deprecation.
* Pull in #373 to have better behavior with UUID primary keys, etc.

Finally, I have my text editor set up to remove trailing whitespace and ensure a ending newline in the files I work on. In the case of sublime text, the settings are:

```json
	"trim_trailing_white_space_on_save": true,
	"ensure_newline_at_eof_on_save": true
```

I find that having this practice results in simpler and more correct diffs overall, and better behavior with various tools. If you're not into that, I can rework the pull request, but honestly, it's just a good practice.