labhub.py: Incorrect implementation for `is_room_member`

[abhishalya]

The gitter backend returns a list of GitterRoomOccupant, but in the function we consider it to be a list of strings.

https://github.com/coala/corobo/blob/master/plugins/labhub.py#L113

type/bug difficulty/newcomer

[Arna-Maity]

@abhishalya I am a newcomer and would like to work on this issue. Could you please assign it to me ?

[abhishalya]

@Arna-Maity I've invited you, once you've accepted the invitation I can assign you to this issue.

[Arna-Maity]

@abhishalya i have accepted the invitation.

[abhishalya]

Assigned