react-bootstrap dropdowns are not good for >5 options

[sersorrel]

Instead of the react-bootstrap dropdowns, react-select dropdowns should probably be used in many more places; they allow typeahead/result filtering, and scroll rather than overflowing off the viewport.

Style-wise, they don't fit terribly well with the rest of the application, but a) that's probably fixable, and b) the Bootstrap 3 style is not necessarily something to strive for anyway.

• "Other Project" dropdown on finalisation screen
• "Other Supervisor" dropdown on finalisation screen
• "Select supervisor" dropdown in project editor
• student selection dropdown in project editor
• Anywhere else?

[piyushahuja]

The dropdowns in project editor have been changed, the ones on finalization screen dont appear too pretty next to rest of the elements.