Provide single point for enforcing config naming convention

Provide single point for enforcing config naming convention

- Provide generic ConfigurationObject class which other will extend
- Class provides method for validate string based on default private regex
- Regex enforces 1 to 256 alphanumeric chars with addition of -+/*.()[]@
- Default regex can be overwritten with one set in config.ini
- Have configs which need name validation to extend new class.
  Change is bacward compatible, existing config file are correctly
  deserialized

Change-Id: I17714fc6b0462fc2a85e9a6d8f44fd7f0bbda188
Signed-off-by: Alessandro Boch <aboch@cisco.com>