Lock the version of virtualenv.

The latest version of virtualenv install pip 1.5 which uses distlib which expects
a home directory where it can create a '.distlib' directory.

See: https://bitbucket.org/pypa/distlib/issue/39/using-distlib-with-pip-fails-when-usre-has
Explicitly set the npm registry.
adding vars for cert key files
changing instance type to small
updating ami for https support with valid cert
back to medium
Use npm config instead of editing rc files directly.
Merge pull request #605 from edx/jarv/add-star-cert

Jarv/add star cert
Merge pull request #603 from edx/feanil/lock_virtualenv

Feanil/lock virtualenv
adding course_data_path for ora
Merge pull request #608 from edx/jarv/ora-course-dir

adding course_data_path for ora
deploy gerrit server using pre-built binaries

Includes several notable limitations:

* The postgres RDS instance has to be manually created before running the play
* The secure variables have to be defined on the command line
* Gerrit runs on port 8080, instead of 80.  Using 80 is a bit complicated.
* Email doesn't work since I don't know what SMTP server to use (maybe SES?)