Sync common config module from Oslo

List of changes

1a6dfb9 Sanitize FQDN in config generator
e839886 Config generator fails with lazy messages
763eedf Fix DictOpt support in config sample generator
e3dddd7 generator: use EXTRA_* env vars in the bash script
e8e636c generator: add an EXTRA_LIBRARIES env variable
5dce17b Use entry points to discover options in libraries
dd9aa2b Remove unused variables
ad17a69 Fix filter() usage due to python 3 compability
7c18261 Temporary workaround for config generator
4b3e32b Sort the output of config/generator.py by group name
12bcdb7 Remove vim header
806272e Improve error reporting on import failures
6cd1c33 Clean up extra modules code

Updated ironic.conf.sample using new config generator.

Closes-Bug: #1282481
Change-Id: Ice3e527589bbf0e881d21f55229264513ea445d2
Merge "Sync common config module from Oslo"