CIMI: Tests - minor changes to support other providers

TrackedAt: http://tracker.deltacloud.org/patch/ac660beed6738e8f3021f709024cbef54f7ec267
Tests: buckets_test.rb - adding check to cleanup for whether the collection is supported

TrackedAt: http://tracker.deltacloud.org/patch/727f1e3ce313b594d8b85a2e5db9728b6a5dc6f3
CIMI - Tests - cleanly skip CIMI Resource Metadata tests for unsupported capabilities DTACLOUD-471

TrackedAt: http://tracker.deltacloud.org/patch/5ef613dcee21edad280a0ae935182ec29d54054c
CIMI - Tests - review corrections for set 329

TrackedAt: http://tracker.deltacloud.org/patch/bd302075e2484fa79794310ca857b351e963cdcd
CIMI - minor tidy up/nits in parsing of database models

(related to DTACLOUD-448)