removing commented out roles in the sandbox play

forum role cleanup

Fixing upstart script to source env.

* consistent jinja variable syntax
* comment blocks on the tasks/main.yml files
* some syntax errors, variable name issues
* indenting, breaking up long lines
* various bug fixes

fixing handling of ssh keys

DO NOT MERGE: initial commit of forum related roles

Use different port for each service.

Feanil/multiple vagrants

for edxapp, install python sandbox requirements into regular venv

Initial definition of the worker boxes in cloudformation.

Extract the app port numbers into the vars file.

The number of workers need a multiplier, which I missed in code review

temporary fix to allow some things that depend on this (like
drag-and-drop questions) to not break.  Also, this configuration
might be what trial installs prefer, anyway.

Make the condition on migrate_db a bit safer for using in var_prompt