Clean up source file headers (resolves #309, #310)

[fnothaft]

Makes two changes:

• Attaches the ASF suggested license file header to all source files. This license header attributes copyright to the Regents of the University of California. Let me know if someone would like the copyright changed; I have this scripted, so it is a quick change. We'd probably want to add a NOTICES.txt file if making the copyright more specific.
• Removes @author tags, as per discussion with @benedictpaten @hannes-ucsc on today's scrum.

[heuermh]

+1

[hannes-ucsc]

Should we do this in Toil, too?

[fnothaft]

I generally prefer the Regents of the University of California copyright—esp. if you have contributors from multiple UCs—but I'm not picky.

[hannes-ucsc]

Build fails with

pip2.7 install -e .
Obtaining file:///mnt/ephemeral/workspace/toil-scripts
    Complete output from command python setup.py egg_info:
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/mnt/ephemeral/workspace/toil-scripts/setup.py", line 23, in <module>
        from version import version
      File "version.py", line 2
    SyntaxError: Non-ASCII character '\xe2' in file version.py on line 2, but no encoding declared; see http://python.org/dev/peps/pep-0263/ for details

[fnothaft]

Build fails with

Hah! I got cocky and used an en dash instead of a hyphen in 2015–2016. Will fix.

[fnothaft]

Rebased and addressed buld issue.