Ensuring openstudio.exe discovery process on Windows is reflected in Appveyor

[rHorsey]

General Issue / Feature Information

Description

There has been a bug due to Appveyor being unable to find openstudio.exe. See #403 for the log file in question. It's unclear how the openstudio.exe file should be found on the appveyor file system. @axelstudios suggests that setting $PATH may not actually reflect how OpenStudio itself installs on Windows. Given this, I would like to ensure some degree of parity in the testing environment regarding how openstudio.exe discovery.

Expected outcome:

OpenStudio install process configuration reflected in how the openstudio.exe file location is specified in the Appveyor environment.

Other information (i.e. issue is intermittent):

This issue may/should result in explicit tests regarding discovery of openstudio.exe.

[rHorsey]

This is being addressed by two PRs: #393 and NREL/OpenStudio-PAT#95 - the phillosphy is that PAT knows where the openstudio cli exe is, just as it knows where the energyplus exe is, and so the openstudio cli exe will be passed to the child processes as an envvar through the meta-cli, just as the energyplus exe is.

[rHorsey]

Completed by PR #407