[48482829] remove cancel button shown on user create and edit page

Also remove Filled Seats from 'edit job opening' page.

Signed-off-by: Henry Chen <hchen@vmware.com>
more code refine

1 remove depracated interview.title;
2 ensure Opening.department a mandatory field
3 remove 'filled seats' from UI

Signed-off-by: Henry Chen <hchen@vmware.com>
Merge branch 'master' of https://github.com/vmw-tmpst/heroapp-LetsHire into validator
Merge pull request #129 from Henry-CF/code_refine

[49372363] remove title from interview table