Minor Fixes and layout improvement

UPDATE

• ADD transition to sortable tables
• ADD table with div for sortable pages
• ADD transition to sortable
• Add loader for structure sortable index
• Separate fielg group parent settings from repeaters ones
• Update readme

FIX

• Reduce complexity
• FIX fieldgroup layout
• FIX codeclimate config file
• FIX choice
• FIX field group slug not being save on field group creation
• FIX structure sortable index table
• FIX odd transition of shadows when hovering sortable row, AND add flex layout
• FIX structures title
• FIX row td width 1of2
• FIX issue Sortable without shadow on Safari #138