Automatically validate parameters when parsing config files

Create inspections to check configuration parameters:
* check that parameter value has appropriate type and format
* check that parameter value is consistent with configurations of corresponding services

This code will be eventually contributed to Oslo.config library. We plan to re-use Oslo.config with capabilities we contribute to it.

Oslo blueprint to track the progress of this contribution is:
https://blueprints.launchpad.net/oslo/+spec/oslo-config-options-validation