Allow admin user to get all tenant's floating IPs

When getting floatingips with Nova API, the results will be filtered
with the 'tenant_id'.
So, we can only get the floatingips belonging to the tenant of the current
context.
When ceilometer invokes novaclient to list floatingips, it will get an
empty list because the tenant is 'service'.
we should allow an admin user to index all tenants's floatingip by adding a
parameter 'all_tenants'.
This patch provides CLI support

Change-Id: I35a2155401247d49017bf3c03341b082cb87750d
Closes-bug: #1262124
Fix name arg help for volume-type-create

Similar to change I10b1bd6d but for help on an argument rather than the
command itself.

Closes-Bug: #1304570

Change-Id: I4f08ffb6af248ccd7446012765d17c41567f4b38
Merge "Allow admin user to get all tenant's floating IPs"
Merge "Fix name arg help for volume-type-create"