#60 updated bootstrap dependency to 3.3.0
#60 changed label  'Icc objects' to 'Indicator files'
 #60 file choosers in bootstrap look

hide the file choosers for loading criteria functions and decision
strategies behind a bootstrap button. use the space right of the button
to indicate errors or show the loaded file.
 #60 several ui improvements

- remove selection button is disabled when no indicator files are
  selected
- indicator files are selected per default when added
- load cf and ds buttons are disabled as long as no indicator files are
  selected
 #60 integrity checks when laoding files

when loading indicator, criteria functions or decision strategies, we
check if the ojects to load contain all necessary information belonging
to the indicators of the first loaded indicator file.
 close #60 stlyed error msg of file chooser
Merge branch 'feature/60-ui-improvements-file-provider' into dev