Minor bug fixes and 1 new option

• Fix: Shortcode was using echo and is now using return instead.
• Fix: Position of inner wrapper changed to relative to contain dropdown menu´.
• Update: #sagaio-udm-menu-wrapper changed name to #sagaio-udm-menu-inner-wrapper.
• New: Added outer wrapper and options for configuring its position, id: #sagaio-udm-menu-wrapper.