CLOUDSTACK-6940:Templates cannot be downloaded from URLs without
matching file extensions.
CLOUDSTACK-6941: Can't choose storage for the volume, when attaching uploaded data volume to VM

Changes:
- Only way to choose a certain storage pool is by using disk_offering_tags
- Added a parameter to take in a disk offering Id.
- Admin will have to create a custom sized disk offering and tag it as necessary for the user
- This custom offering Id should be passed during uploadVolume to associate the volume with this disk offering