Make category selection a separate step

After package file is upload, user should point to witch category this package belongs.
Now, it's not obvious that this parameter is requred and user don't undestand
what he needs to do. Making a separate step for category selection will make that clear.
Also, templates for that forms were updated.

Closes-Bug: #1394572
Change-Id: Iec964a5b09602b465e76a537344d3a900478cc96
Merge "Make category selection a separate step"