Updated to work with Django 1.7

Major changes:
-----------------------------

- Made changes to the way the modules are laid out:
  Instead of:
  ```
    redwood/
        __init__.py (for redwood)
        (redwood module files)
        expecon/
            __init__.py (for expecon)
            (expecon module files)
  ```
  We now have:
  ```
    redwood/
        redwood/
            __init__.py (for redwood)
            (redwood module files)
        expecon/
            __init__.py (for expecon)
            (expecon module files)
  ```
  This way there are no nested modules, which can be potentially confusing. Also, this is what the default layout for modern Django projects is.

- Modified the setup script to install Django through pip.

- Removed django-reversion from the repository and added some lines to the setup script which install the django-reversion package through pip.

- All of the static files have been moved from static/ to expecon/static, these can be copied into static/ by manage.py collectstatic.

- Removed the old Django admin CSS/JS files from the repository (they were in static/)

Besides these, most of the changes amount to changing imports to reflect new module locations.