Allow greater customization of search page

The changes in my fork are solely for the ability to easily change the design/layout of the 'search.html' template. Prior to my changes the search form was built in main/forms.py using the Django Forms API. This approach is clean and concise but locks the developer in to the 'CheckboxMultiple' input type which may or may not be the best experience for a person trying to search.

This is my rationale for the pull request. Please contact me at cory.dissinger@gmail.com with any questions.