Ignore .env files.

It is common to store private configuration data in .env files.
In this case, we allow for the option of storing private XTC
information in a .env file in test/xtc.
Adds CI script for submitting XTC job
Adds XTC submit step to local-run-as-travis
Adds stubs for XTC job in Travis CI

Testing has shown that we need a device set strategy.
This CI step is disabled for now.