Delete group member behaviour

[sharathkumaranbu]

Right now we allow only Admins to access delete group member end point

https://github.com/topcoder-platform/groups-api/blob/7475dde7bb9e02b670c80745bc145152e9b93dd4/src/routes.js#L86-L93

But in the code we have logic in place to allow a member to delete himself from self registration enabled groups.

https://github.com/topcoder-platform/groups-api/blob/7475dde7bb9e02b670c80745bc145152e9b93dd4/src/services/GroupMembershipService.js#L158-L164

What is the expected behaviour here @cwdcwd @dushyantb ?

[lakshmiathreya]

cc @lakshmiathreya