Merge pull request #74 from edx/dev

Dev
Merge pull request #75 from edx/dev

Slight docs update
Cloudformation and settings updates
More cloudfront changes
Change security
Allow bastion to use ssh so it can grab github stuff
Remove some subnet config
Add another port to template
Cloud security groups
Update apt packages
Merge remote-tracking branch 'origin/dev' into dev
Cloudformation fixes
Open right port on elb security group
open elb port for rabbit
Template port updates
fix comma in template
Output S3 bucket name from cloudformation and read in aws keys in aws settings to configure ml to save to s3
Wire through S3 settings
Open up port 80 and 443 for egress by ml api so that it can connect to S3 for model storage
elb in both public subnets