pool resize enhancement

Add the ability to remove disks from an existing pool during pool resize
Merge branch 'issue#299_resize_pool' of https://github.com/kamal-gade/rockstor-core into kamal-gade-issue#299_resize_pool
Merge branch 'issue#299_resize_pool' of https://github.com/kamal-gade/rockstor-core
Merge branch 'master' into kamal-gade-issue#299_resize_pool
Merge branch 'master' into kamal-gade-issue#299_resize_pool
force add drive if need to. #299
use PUT instead of DELETE for disk removal. #299
Refactor pool view for resize. #299
Add integration tests for pool ops. #299
Update front end to send disks as list for add pool. #299
Update frontend to send disks as list when adding disks to a pool.
update help message in pool resize. #299
Don't force add disks with existing btrfs filesystems during pool resize. #299
Deprecate the buggy remove_pool logic. #299.
remove pool should not really wipe the disks, just update state/db. #299
Remove deprecated setupwizard view. #299.
Scan disks during setup, and fix error display

Add scanDisks function and call it during in method chain after
successful login during setup
Add error template overlay to setup.html for common error message
display
Attach resize handler to resize button only once
Do disk rescan on get so clients always get most accurate information. #299
Merge pull request #503 from kamal-gade/issue#299_resize_pool

issue#299 pool resize enhancement