Enhancement: Add a reference parameter to the getQuota request

Implementation of [cs3org/cs3apis#147](https://github.com/cs3org/cs3apis/pull/147)

Make the cs3apis accept a Reference in the getQuota Request to limit the call to a specific storage space.

https://github.com/cs3org/reva/pull/2152
https://github.com/cs3org/reva/pull/2178
https://github.com/cs3org/reva/pull/2187
