The oslo.cache library was introduced to support metadata caching[1],
but its parameters have been missing from the configuration file
generated by oslo-config-generator.
This change adds the missing oslo.config.opts endpoint so that
the parameters of the oslo.cache library are automatically rendered.
Change-Id: Iede57b7c86012951ee934ee9f56694e108f1b51a
Takashi Kajinami