WSGI log files use a different input configuration than OpenStack log
files. Currently this depends on log files matching either *-access.log
or *-error.log. Some services use *_access.log or *_error.log, so are
not parsed correctly.

This change modifies the fluentd configuration to accept an underscore
or hyphen for WSGI log file names.

Change-Id: I566d6cac0b6749054fd5422ec8f36f99dacb1db7
Closes-Bug: #1720371