Enable Display NEM Address to Allow Tipping

NEMHub should allow users to make their NEM addresses visible to the public, with QR Code.
Users could then tip each other with desktop & mobile wallets. 

By default, addresses would remain hidden. Each user would have to enable tipping for their address to display.
Additionally, a browser-based NEM wallet extension would allow seamless tipping integration.

Tipping would stimulate quality submissions to NEMHub, as users have the potential of receiving tips directly from community.