* 2.1.0 - Nov 18 2015
- For auto-generated temporary requirements.txt file, use the virtualenv directory instead of parent temp directory to keep things cleaner and isolated
- Allow specifying a temporary directory on the enableOnDemandImporter call.

* 2.0.1 - Nov 17 2015
- Split up module into a couple files
- Split out the package installation from env creation, to support adding to
existing envs
- Add support for enabling automatically trying to install modules after
failed import, by calling "VirtualEnvOnDemand.enableOnDemandImporter()"
- Update docs accordingly
