Moved redwood module into a subdirectory

Moved settings.py and urls.py into a subdirectory so that there
are no nested python modules.
updated manage.py
Removed django-reversion

- Removed django-reversion code from the repository
- Added lines to setup script to install django-reversion package
- removed admin.autodiscover() since django 1.7 does this automatically
- added "apt-get install sendmail" to setup script because the default
  logging settings crash without it.
fixed url errors
added allowed hosts to settings
Added view_on_site to session inline admin
Changed CWD to BASE_DIR in settings

CWD pointed to the current directory of the settings.py file,
BASE_DIR points to the directory containing that directory.
Moved static files from static/ to expecon/static

The static root should not be kept in the repository, since it's
contents are populated by the collectstatic command.
changed email in settings to a placeholder
changed mimetype to content_type
Merge branch 'django' of https://github.com/LeepsLab/RedwoodFramework into JeremyDev
Updated django.wsgi for django 1.7