Added doctest for getting group keys.
Added documentation.

Added
-----
* Added lots of new examplesand doctests.
* Fomatted for numpydoc.

Changed
-------
* Methods that take ids as arguments should be able to accept a scalar,
  array-like, or nothing to indicate a single id, a set of ids, or all
  ids, respectively. Going through and updating this where possible.
Changed decorators to use functools.wraps.
Added more documentation and doctests.
Changed unit_test to _unit_test.
Updated rst files with sphinx-apidoc.
Minor comment
Adding tutorial and documentation

Adding documentation and edit users_guide to edit what
few components do (Ecohydrologic components only)
Adding figures for radiation field tutorial

adding figures (outputs) for radiation field tutorial
Used sphinx API doc force

used API DOC force to update sphinx files
deleting unwanted files_ test

testing removal of unwanted files
removed some RST files and updating tutorial

removed some unwanted RST files and updated radiation_field tutorial
RST reference in index.rst

updated index.rst to point to the right radiation tutorial
minor updates to rst

minor updates to radiation tutorial
Minor formatting tweak for docs
typo
Merge pull request #1 from landlab/master

merging
Minor doc tweaks

Light editing on tutorial.rst and radiation_field.rst
Added Travis configuration file.
Changed to install numpy/scipy with apt-get.