Added new documentation theme.

Added
=====

* Added the scipy documentation theme. It seems to look nicer with
  the numpydoc-style docstrings.
Added Attributes section to ModelGrid.
Added deprecation warnings; more docs.
Changed DEBUG_VERBOSE and DEBUG_TRACK_METHOD.

Changed
=======

* DEBUG_VERBOSE and DEBUG_TRACK_METHOD are now _DEBUG_VERBOSE and
  _DEBUG_TRACK_METHOD.
Changed DEBUG_TRACK_METHODS to _DEBUG_TRACK_METHODS.
Added new documentation theme.

Added
=====

* Added the scipy documentation theme. It seems to look nicer with
  the numpydoc-style docstrings.
Added Attributes section to ModelGrid.
Added deprecation warnings; more docs.
Changed DEBUG_VERBOSE and DEBUG_TRACK_METHOD.

Changed
=======

* DEBUG_VERBOSE and DEBUG_TRACK_METHOD are now _DEBUG_VERBOSE and
  _DEBUG_TRACK_METHOD.
Changed DEBUG_TRACK_METHODS to _DEBUG_TRACK_METHODS.
Minor documentation updates.
Added new methods has_field, keys, size.
Added some minor documentation changes.
Added sphinx.ext.autosummary extension.
Added documentation for fields.
Merge branch 'fix-model-grid-docs' of github.com:mcflugen/landlab into fix-model-grid-docs

Conflicts:
	landlab/grid/base.py
	landlab/grid/raster.py
Merge pull request #24 from mcflugen/fix-model-grid-docs

Fix model grid docs