Add NOTICE file. Closes #22.
Add license notice to files that were missing it

One liner to find files that are missing the header:

for i in $(find . | grep '\.scala') ; do echo $i $(head -n 2 $i | tail -n 1 | grep Licensed) ; done | grep -v Licensed
Fix package names
fix more package names
Merge pull request #209 from hammerlab/add-license-header-comments

Add license header comments