Modal fixes - 2 columns, padding, header, membership

Adds padding to tab-content which takes care of proper
spacing between tabs and tab-content.
refactors tabs styling - match modal and non-modal tabs
Changes modal header h3 margin to save space.
Cleans up Membership widget styling
Unifies 2 column layout in modals using bootstrap columns
Changes create and update image modal template as an example.
The rest of the views is changed in subsequent patch

Closes-Bug: #1354505
Change-Id: Idca2a2dbdea8cdacc37061faa52004b1020b1bf0
Merge "Modal fixes - 2 columns, padding, header, membership"