Add GPL exception to license.

The exception allows applets, workflows and plugins extending ilastik
through controlled interfaces to have non GPL compatible licenses.
Change license statements to mention GPL exception.
Add license dialog.
Display license from buildem when running from a binary install.
Binary distribution license path is different for windows.
knime integration, first running version
move operator out to lazyflow
Merge changes from 'master'
Update new file headers with GPL exception.
Merge pull request #871 from burcin/license

Add GPL exception to license.
Fix missing import in ilastik_main.py. Fixes #892.
Comment (OpDataSelection)
Serializer: Don't swallow exceptions during deserialization.
logging: Added a couple handlers.
Fixed headless test
Serializer: If a slot can't be deserialized because the project file is missing the group for it, give a warning but don't raise.
Basic server to listen/send messages via TCP in a separate thread
Easy hack to change position in volumina for each applet in current workflow
General function to set viewer position (in 5d) in LayerViewerGui
Implementation of setAllViewersPosition() in ilastik shell; switch from raw text to json message for TCP server