Sync latest config file generator from oslo-incubator

The fix to the config file generator to support lazy messages
is the main addition of interest because it is needed before
lazy messages can be enabled in Nova.

Commits included:

  1a6dfb956 Sanitize FQDN in config generator
  e839886cc Config generator fails with lazy messages
  763eedff6 Fix DictOpt support in config sample generator

Note that these commits do not touch any other files (beyond
oslo testcases).

Partially implements blueprint i18n-messages
Closes-Bug: #1280826

Change-Id: I2174139ba3767d05924747cbefa377ba8780103d
Merge "Sync latest config file generator from oslo-incubator"