Variable number of classes enabled

Added classes for image and image class.
Class loading now based on directory structure - directory names as class
names.
Up to six classes can be used (six colors in plot - can be changed if
necessary).
Image downloading

Added exception handling for the no-response error.
Only first word from the query is used for the class/folder name.
Three classes are downloaded.
Some bug fixes
Merge pull request #1 from sacherus/cl3

Cl3