Remove some unused imports

optparse is unused since 0c0d8f0 and os is unused since f6bc5d0.

Change-Id: I32357293712d30774108041b039410b68a5eb7e0
API extension and DB support for service types

Blueprint quantum-service-type

This patch allows for managing service types through the API.
The default service type is specified in the configuration file.
The patch also provides a 'dummy' API extension, which uses the
'dummy' service plugin, as a PoC for usage of service type.
The dummy API extension is used in unit tests only.

Change-Id: I97d400b941fa7925b0efa0fd0d35c07419ff6bfa
Merge "Remove some unused imports"
Merge "API extension and DB support for service types"