Merge pull request #79 from astaric/travis

Add travis configuration.
Added missing packages and package data entries in setup.py
Changed few labels and PEP-restructured the code.
Merge branch 'master' of github.com:biolab/orange3
Comment to add_origin, removed previous todo mark.
- kNN classifier from scikit moved to script part (orange/classification)
- usage of default scikit learn imputer class to handle NaN; (optional) replace with Orange imputer when implemented.
- added Mahalanobis distance.
Removed long description (too verbose and obvious).
Merge branch 'master' of github.com:biolab/orange3
Create postgres db before install.