Added Pantheon Terminus deployment functionality.

Using Terminus to deploy pantheon sites is awesome, but annoying when you are doing it over and over. This automates the process, allowing you to deploy per environment.

launcher terminus.[site-name].[environment]

ex: launcher terminus.aaimap.test

This would deploy code to the dev and test environment of a site named aaimap. Terminus would run a drush updb, cim, and cr, on each environment.

Meaning in longhand:

terminus env:deploy aaimap.dev
terminus drush aaimap.dev updb
terminus drush aaimap.dev -- cim -y
terminus drush aaimap.dev cr
terminus env:deploy aaimap.test
terminus drush aaimap.test updb
terminus drush aaimap.test -- cim -y
terminus drush aaimap.test cr

Dev deploys to dev.
Test deploys to dev and test.
Live deploys to dev, test and live.