Add project member to project

[gokulan97]

This has to be started once #9 is completed.

The task is similar to displaying the list of colleges as suggestions.
Once the admin types a name, suggestions come, and choosing a user and clicking add adds the particular user to the project members.

It is to be done in three different categories - project leads, mentors, members.

[Rohithram]

is the previous issue done?