Create a Jinja context object with parameters

Allow a template to call the function to set environment variables in
UserData.
Merge pull request #220 from huit/export-vars-to-instance

Create a Jinja context function to pass parameters
Improved Vagrant deploy process

Copy payload and Jinja templated Vagrantfile into a working directory,
with ability to pass custom stack name. Separate box download from
vagrant up, and provide better output. Properly pass through NEPHO_
environment variables to hook scripts.
Fixing destroy/access/status commands

Need to use new directory.  Also prettying up status (and simplifying
since much of it won't work in multi-VM setups)
Catch missing directory on status command
Missing app_obj
Error if parameter is set to None
Merge pull request #221 from huit/improve-vagrant

Make Vagrant as flexible as AWS, fix a few random bugs
Merge branch 'master' into stable
New version 1.2.0 release