[core, mod_cidlookup] Free memory allocated via strdup

[core, mod_cidlookup] Free memory allocated via strdup

In mod_cidlookup and several other modules, config parameters
are read from external XML files using the SWITCH_CONFIG_ITEM_STRING_STRDUP
method.  These items do not have string_options, and are not freed
with switch_xml_config_cleanup.  We therefore need to call switch_safe_free
for config without string_options.  We also add switch_xml_config_cleanup
to mod_cidlookup.  There are other modules that may be affected but this
commit makes no attempt at fixing those.

Fixes #1752