Measure tester gem needs write permission to current directory for temp files

[macumber]

This is in addition to write permission in measure directory. Was messing me up when running from bin directory of openstudio install. We should test for write permission and fail if don't get it. I'd prefer to do all our writing in open place, maybe test_results/tmp folder in measure directory?

[macumber]

Might be a good idea to hack Minitest to cd into measure test directory before running each test