Implement ability to filter clubs

[rucny]

Please do work for this task in a branch named issue-8.

• The site should allow filtering by interest area.
• For example, “athletic” clubs, “art” clubs, “music” clubs, etc.
• It is possible for a club to belong to multiple interest areas.
• An idea is to use the 'type' description from the RIO csv as a starting point.

[kendrick-g]

Added a category dropdown for students to use to filter through clubs. Dropdown contains existing categories of existing clubs to filter through.