CIMI Systems: fix for DTACLOUD-559 - id was not set for SystemMachineCollection and SystemVolumeCollection

https://issues.apache.org/jira/browse/DTACLOUD-559
https://github.com/deltacloud/deltacloud-core/pull/28
https://github.com/deltacloud/deltacloud-core/pull/27
Tests: hard-code minitest < 5.0.0 until 5.0.0 compatibility issues can be looked at in detail
FGCP: read FGCP_CERT_DIR env var in method instead of start of class
to allow unit tests to set it.
The old way stopped working because drivers are now preloaded at startup.