First pass at Iowa datasource

I still need to preprocess the PDF data and wire this in.

Addresses https://github.com/openelections/core/issues/118
Remove incorrect entry for 2010 general election results

The row for the 2010 primary results file was duplicated for the
general election.

Addresses https://github.com/openelections/core/issues/118
Set the reporting level for the 2010 general results file

I forgot to do this in the last commit.

Addresses https://github.com/openelections/core/issues/118
added initial ms datasource and mappings
added ocd_id for specials
ms datasource special election handling
added more 2013 specials to url_paths
added 2012 specials to url_paths
basic general election handling
added 2012 general to url_paths
Merge pull request #182 from EricLagerg/dev

corrected URL paths for us/wa/mappings/url_paths.csv
Merge branch 'dev' of github.com:EricLagerg/core into EricLagerg-dev
Only try to delete a path if it is a directory

Update @EricLagerg's fix for #180 to more carefully check the
``errno`` attribute of the caught ``OSError`` exception and
only try to use shutil.rmtree if the OSError was raised
because the file is a directory.

This helps prevent getting other instances where OSError would be
raised, for instance a file permission error, from getting eaten.

Addresses https://github.com/openelections/core/issues/180
Merge branch 'EricLagerg-dev' into dev
Remove nested zip files

When extracting nested zip files, remove the zip file, the parent
zip file and any extracted directories after extracting the target
file.

Addresses https://github.com/openelections/core/issues/180
fixed datasource for 2010-2011 elections
Merge branch 'dev' of github.com:openelections/core into dev
fixed WV loader for 2008-2011 elections
2000 loader
added precinct segment to 2012 results files