Create dropdown for committee when creating events

[alexanderqchen]

Motivation

Currently there is no validation on what committee users choose when creating events. This caused a lot of inconsistencies (e.g. ACM-W and W are 2 different "committees").

To Do

• [ ] Add a committees section to the config.js file This can just be taken from here.

• [ ] Add a committee named "General" to this list for general ACM events

• [ ] Create a dropdown that allows admins to choose a committee when creating an event The options for which committee to choose can be taken from the config.js file (in the committees section you just created).

[alexanderqchen]

https://github.com/uclaacm/membership-portal-ui/pull/68

[howardwang15]

Assigned to Sai, checkout add-event-dropdown, fix colors on buttons