removes slugfight from Park model

let it be up to the content editor to find good slug, slugfight in
custom save method is causing problems.
fixes problem when new park couldnt't be saved

because had no PK yet when trying to add neighborhood M2M.
makes area field on park model class nullable
Adding thumbnails to the admin list, and change_view
Adding in thumbs to resource, adding in settings for thumbnail width, and calculation functions for getting the thumbnails in the models.
Fix zoom level on map to show REALLY SMALL
Adding Typeahead functionality
Added new fields that pop up on facilitiy info windows
Fix the problem where facility types being empty, shows all parks.
Add links to park in stories on home page
Closes #112   Adding all to Neighborhoods in Play on the home page.
Functionally add the "all" to the neighborhoods in the play dropdown.
Broken parkmap.js
add search to home page
Made search based on slug, and fixed parks not loading
Make the home search go to the explore page
Add icon images to facility type, need to be able to read them still
change parkmap on explore, and make icons required
closes #107
Fixing some PLAY! changes, as well as making the model required.