Replace '_' with '_LI', '_LE', '_LW', '_LC'

oslo.i18n uses different marker functions to separate the
translatable messages into different catalogs, which the translation
teams can prioritize translating. For details, please refer to:
http://docs.openstack.org/developer/oslo.i18n/guidelines.html#guidelines-for-use-in-openstack

Added hacking rules for warning, info, critical, error and exception
about checking translation for log messages and fixed for below cases only,
1. LOG.error(_(""))
2. LOG.info(_(""))
3. LOG.exception(_(""))
4. LOG.critical(_(""))
5. LOG.warning(_(""))

Below scenario is not handled in this patch,
If message is passed to LOG call using separate variable,
ex.
    msg = (_("")
    LOG.error(msg)

Change-Id: Idbf8779cdfc41ca1424bebcd101096bec482872f
Merge "Replace '_' with '_LI', '_LE', '_LW', '_LC'"