[cloudstack] add disk_offerings, os_types mock data
[cloudstack] add list_os_types, list_disk_offerings request mocks
[cloudstack] list_os_types, list_disk_offerings request tests, rm pending
Merge pull request #1750 from dm1try/cloudstack_add_list_os_types_and_list_disk_offerings_mocks

[cloudstack] Add list os types and list disk offerings mocks