Switch from python-gnupg to gnupg, update calls

* "gnupg" is a fork of python-gnupg which seems more actively maintained and
  more responsive to bug reports than python-gnupg
* Updates to the latest version of gnupg and updates gnupg calls to
  preserve semantics where the API changed
Fix nose tests to work with updated gnupg API
Settings tweaks to get certs to run on Mac OS X
Merge pull request #15 from caesar2164/giulio/settings-fixes

Settings tweaks to get certs to run on Mac OS X
Add stv to AUTHORS
Merge pull request #18 from stvstnfrd/author

Add stv to AUTHORS
Merge pull request #13 from edx/jrbl/bugfix_gpg

Switch from python-gnupg to gnupg, update calls
Update requirements to use more modern stuff

* bump reportlab from 2.6 to 3.1.8, a painless drop-in upgrade
* bump requests from 0.14.1 to 2.3.0, making it match the version in use
  on edx-platform. Some small code updates to make this work.
* bump PyPDF2 from 1.19 to 1.23, a transparent upgrade
* remove logging-config dependency, it appeared unused
* remove lockfile dependency, it appeared unused
* remove python-daemon dependency, it appeared unused
* remove simples3 dependency, it appeared unused
* remove wsgiref dependency, it appeared unused
* Trivial import cleanups
* Introduce DEFAULT_ORG variable, so that LONG_ORG configuration no
  longer fails with poorly configured test courses. This also saves
  sites whose certs all issue from one org from having to configure the
  org in every cert.