fix loading of keywords for pictures in helper
fix bug where strong coocurrences cannot be found and KeyError is raised
change subcluster structure to include tags to represent mcl cluster
Change file path to file name in metadata objects

currently we wrote the whole path of a json file into helping data structures
now only the file name is saved therefore the name had to be changed
from file path to file name
adjust frontend to still work as before with changed data structure
Merge branch 'master' of github.com:nicolas-fricke/semmul2013-group1
do not display empty tree nodes with new data structure
Implement convert pickle to json

because we are trying to use jsons but until now have only the preprocessed pickles
Merge branch 'master' of github.com:nicolas-fricke/semmul2013-group1
fix bug with subset checking and new data structure
Merge branch 'master' of github.com:nicolas-fricke/semmul2013-group1
Fix bug, file name instead of file path does not work

because of preprocessed data
Merge branch 'master' into use_newly_extracted_visuals

Conflicts:
	src/clustering/visual/combined_clustering.py