Add Ricky to list
Tweak MLT code; add docs

* tweaks the MLT class so that s isn't required anymore
* adds an es argument
* adds documentation
* adds two more tests to make sure the s vs. index/doctype works
  correctly
Issue 54. Add docs for order-by

This also adds API documentation. It's not great because the docstrings
need work, but it's better!
Re-add index to TOC.
Tweak the search chapter title

Since it uses the ES Search API, it's better to call it "Searching
with S" rather than "Querying with S".
Update CHANGELOG; prepare for v0.5 release
Set version to 0.6.dev
Add James Socol to CONTRIBUTORS

Bah--he contributed ages ago and I missed adding him.
Change _decorate_with_metadata to be less private
Implement MappingType and rewrite everything around it

tl;dr: This is a big rewrite with huge API-breaking changes.

This replaces the old model-type system with the new MappingType
system. This adds a degree of separation between models (traditionally
stored in a db) and documents (stored in ElasticSearch).

Untyped S works just like in v0.4 with the exception that if you
don't specify values_dict or values_list, you now get back a list
of DefaultMappingType which are slightly more useful than dicts.

You can now create an S typed by a MappingType which makes it easier
to specify the index and doctype, but also allows you to tie
business logic to search results and also tie that back to db
objects in a lazy-loading way. For example, say you had a description
field and wanted to have a truncated version of it::

    class MyMappingType(MappingType):
        def description_truncated(self):
            return self.description[:100]

    res = list(S(MyMappingType).query(description__text='stormy night'))[0]

    print res.description_truncated()

Also, inextricably linked with this commit is a minor rewrite of the
test suite. They should run faster now, are better organized, and should
be easier to write in the future. test_django.py doesn't look like it
was written by a shrewdness of apes any more.

Also fixed a bug where `fields` was affected by ``values_list`` and
``values_dict`` calls---the two need to be separated.
Issue 70. Fix date_histogram handling.

* add handling for date_histogram in facet_counts
* fix facet_counts to raise an exception rather than silently act
  dumb if it doesn't recognize the _type
Add note about caching/speed in filter vs. query
Tweak the filter caching text further.
Issue 74. Fix F operand mutations

Operations on F shouldn't mutate the operands. This fixes the code
so it does a deepcopy of the filters before doing things with them.
Add note about id and .index()
Add note about refreshing after indexing.
Fix es_required_or_50x decorator

This tweaks the es_required_or_50x decorator to handle other ElasticSearch
errors and also improves the documentation. It also allows for template
overrides and nixes the msg arguments--they seemed less flexible.

Note: These decorators have no tests in the test suite, yet.
Fix error from last commit

It's MaxRetryError--not MaxRetryException.
Update CHANGELOG
Add Giorgos to CONTRIBUTORS list