Update oslo-incubator log module

Changes -
 * Use hacking import_exceptions for gettextutils._
 * Correct invalid docstrings
 * Remove keystone from default_log_levels default

Change-Id: Ic8d8c156b80c8347e2333aa8745185e4a6d08b40
Update oslo-incubator periodic_task module

Changes -
 * Use hacking import_exceptions for gettextutils._

Change-Id: Ic298e8fa1745d72c1809f6819d384d42cffd43fe
Merge "Update oslo-incubator log module"
Merge "Update oslo-incubator periodic_task module"