Convert to Argparse and do some general cleanup
Get rid of set_ and is_enabled_ functions
More cleanup and pep8 fixes
PEP8 fixes
Remove bindings from email_to_cybox script directory
WIP: clean up header parsing logic
Verify only allowed header fields are used
WIP: add support for email attachments via new api
Merge branch 'master' into email_to_cybox2.0
Updated email_to_cybox to work with CybOX 2.0

This is a huge commit, but it pretty much had to all be done at once.
Add program-specific ID namespace to the output
Remove spurious output
Got a bit excited about that 'A' key
Clean up input and output parameters.

Input is now a mandatory positional argument ('-' is allowed for STDIN)
Output is sent to STDOUT (can be redirected)
Logging messages are sent to STDERR if -v flag is set
Clean up some bugs

Add header to XML files
Remvoe type from URI objects
Change Contained_In to Contained_Within
Merge remote-tracking branch 'origin/master' into email_to_cybox2.0
Update email_to_cybox README to v2.0.0