While creating auto provisioned volume, support added to automatically
calculate the distribute count based on max brick size specified in
the request.
For example, below command creates 2x3(Distributed replicate) volume
```
glustercli volume create gv1 --replica 3 --size 1G \
--max-brick-size 512M
```
Fixes: #999
Signed-off-by: Aravinda VK <avishwan@redhat.com>