First part of courseware refactor

Delete settings.py in favor of envs/*.py, and add a rake task to run a d...

fix multicourse; fix bug in I4xSystem - self.filestore not set when

Don't pipeline in dev environment, which means that there is no need to run collectstatic either. Hooray\!

Delete settings.py in favor of envs/*.py, and add a rake task to run a dev server locally from those settings

Conflicts:
	static/css
	static/css/application.css

to show quickedit when settings.QUICKEDIT is True.  add
mathjax_include.html because that is needed by quickedit.html

filestore not None.  mitxhome.html now properly automatically lists
all courses given in settings.COURSE_SETTINGS.  mitxhome now served
from multicourse.views.  optioninput.html was missing; fixed. cleaned
up access to request.session for coursename in courseware/views.py

More code transitioned to pyfilesystem

Added comments to Askbot stylesheets

Conflicts:
	envs/dev.py

Conflicts:
	envs/dev.py
	sass/README
	static/css
	static/css/application.css
	static/css/marketing-ie.css
	static/css/marketing.css

Specific error handling

Conflicts:
	djangoapps/multicourse/__init__.py
	requirements.txt
	sass/_info.scss
	sass/_textbook.scss
	sass/courseware/_sequence-nav.scss
	sass/courseware/_video.scss
	sass/index/_base.scss
	sass/index/_extends.scss
	sass/index/_footer.scss
	sass/index/_header.scss
	sass/index/_index.scss
	sass/index/_variables.scss
	sass/layout/_calculator.scss
	sass/print.scss
	static/css
	static/css/application.css
	static/css/marketing.css
	templates/main.html
	templates/marketing.html
	templates/sass/index/_base.scss
	templates/sass/index/_extends.scss
	templates/sass/index/_footer.scss
	templates/sass/index/_header.scss
	templates/sass/index/_index.scss
	templates/sass/index/_variables.scss
	templates/sass/marketing/_base.scss
	templates/sass/marketing/_extends.scss
	templates/sass/marketing/_footer.scss
	templates/sass/marketing/_header.scss
	templates/sass/marketing/_index.scss
	templates/sass/marketing/_variables.scss

You can run this by do:

    bundle install (first time only)
    bundle exec guard