Huge models refactoring

res/ui/addCommunityDialog.ui

src/cutecoin/gui/addAccountDialog.py

src/cutecoin/gui/addCommunityDialog.py

src/cutecoin/models/account/__init__.py

src/cutecoin/models/account/communities/__init__.py

src/cutecoin/models/account/communities/itemModel.py

src/cutecoin/models/account/communities/listModel.py

src/cutecoin/models/account/communities/treeModel.py

src/cutecoin/models/community/__init__.py

src/cutecoin/models/community/itemModel.py

src/cutecoin/models/community/treeModel.py

src/cutecoin/models/node/__init__.py

src/cutecoin/models/node/itemModel.py