Support for search_type query string param to searches.

Conflicts:
	elasticutils/__init__.py
Fix cloning S with search_type, add tests
Change search_type to be a chainable method
Expand comments
Explicitly ask Elasticsearch for two shards

At least two shards are necessary for testing query_and_fetch search
type. Make sure that even if the global ES configuration only specifies
one shard, the test still works.
Added support for a `size` parameter to facets.

Fixes #192.

You can now limit the number of facets returned by passing the `size` parameter:

>>> s.facet('category', size=5).facet_counts()

Signed-off-by: Kevin Stone <kevinastone@gmail.com>
IndexerTasks: Add additional kwargs.
Add support for parsing dates with microseconds
IndexerTasks: Swap order of kwargs in indexer task.
Add tox.ini and fix dev requirements
Fix test refresh so it waits until cluster is yellow
Update CHANGELOG, CONTRIBUTORS and add note about facets attribute
Merge pull request #197 from davidlundgren/IndexerTasks-AddKwargs

IndexerTasks: Add additional kwargs.
Add new contributor
Update CHANGELOG
Expand the documentation
Added rst documentation for the facet size keyword argument.

Signed-off-by: Kevin Stone <kevinastone@gmail.com>
Updated searching documentation to describe size keyword parameter to facet()

Signed-off-by: Kevin Stone <kevinastone@gmail.com>
Added unit test to validate that facet() passes through the size keyword argument.

Signed-off-by: Kevin Stone <kevinastone@gmail.com>
Add microsecond test for `to_python`