Started to convert KnowledgeModel to NoSQL-DB
Fix knowledge model so far

one can add and view knowledge now (again)
Reset data
Optimize output
Reload view after new knowledge was added
fixup
one can add new tags to the database
comment out prints
fixup
fixup
fixup
WIP
TagModel: Implement filling tree from NoSQL-DB
tags can be added as childs
TagModel: Implement deleting tags
NewTagDialog: Adapt for combobox (better fixup!)
MainWindow: Change from tag id from int to str (Better fixup!)
WIP -- Experiments with Indexes and CodernityDB
One can now open the edit dialog for knowledge again
NewKnowledgeDialog: Make compatible with PyQt4