Display appropriate error message when user tries to delete a Share that has
replication turned on.
Add multi-snapshot delete capability to the API.

to delete multiple snapshots, the url should be something like:
/snapshots?id=2,3,4,5

The batch delete snapshots one by one and if an error occurs, it just returns
with the error message.
Merge branch 'issue#405' of github.com:schakrava/rockstor-core into issue#405