add way for admins to keep track of notes per user

[ryanguill]

only available from the room designated as the "admin" room, allow anyone in that room to make a note about a user and have it keep the date/time taken. also allow anyone in that room to see notes about a user.

• !note -add @user {note}
  responds with note added for @user

!note -list @user

• responds with

5 notes for @user
2016-01-02 12:00pm UTC by @author
> lorem ipsum dolor

2016-01-01 12:00pm UTC by @author
> lorem ipsum dolor

or

• there are not yet any notes for @user

!note -list
responds with

• I have notes about the following users: foo, bar
• Should return in date descending order.
• documentation

[ryanguill]

im pretty happy with this so far, but interested to hear if anyone has any suggestions or ideas to improve it, especially from a ux perspective.