Added threading of account loading and blockchain watching so that the UI doesn't freeze anymore

Fixing caching bug with blocks being refreshed only every 5 minutes, even if the blocks changed.

Added the possibility to define a default account

Renaming actions in the member tab
Added a BlockchainInspector thread to check for new blocs and refresh the UI

Removed old files

Fixed a bug when an inputs would be removed from available ones even if the transaction is refused
Added icons
Display community nodes again
Save community nodes and load them when acccessing a community object

Signing on the way. There is a bug becuse of ucoin API using keyword "self", and it's conflicting with python self keyword.

Wallet content now show available sources, while Transactions sent and received will display latest transactions sent and received

Wont run because we have to port Pynacl code to libnacl

todo: implement signature function