Improve edX Performance

[usernamenumber]

_Note:_ You will need access to a cubietruck mini-pc to help with this directly, but advice is always welcome!

edX and edX portal are both now working on the cubietruck, but each take ~20 seconds to load. This needs to be improved.

[usernamenumber]

Advice from @natea:

"""
You might want to take a look at this page which provides some tips on
improving performance / memory consumption of edX.
http://ianhowson.com/open-edx-reducing-memory-consumption.html

Also, do you have adequate swap space configured on the Linux partition?
"""

[usernamenumber]

Success! (or at least improvement)

LMS and CMS on my cubie now take a little over 10 seconds to load the first time, but after that they load in as little as _2-5 seconds_. I would still like to get independent verification of this, but that can be done under #34, so I'll mark this one as done.

I made the following changes:

• Tweaked the edX config in the base image so that LMS starts 2 workers instead of 4
• Added some sysctl tweaks recommended on the cubietruck forums to the provisioning system
• Added a script that sets up a swapfile (cubietruck default setup has no virtual memory!), and a step to run it in the setup instructions

The latter two changes can be seen in cadf142