Fix log filtering

In the "properties" config syntax which we use, we can only give one
Filter - "Filters" does parse, but doesn't have an effect. Therefore we
use StringMatch's RE functionality to match several things.

Author: mohawk2

log4perl_prod.conf

@@ -1,33 +1,17 @@
 log4perl.rootLogger=WARN, OUTPUT, SYSLOG
 
-log4perl.filter.GazelleWarnings                 = Log::Log4perl::Filter::StringMatch
-log4perl.filter.GazelleWarnings.StringToMatch   = failed to writev: -1 errno:32
-log4perl.filter.GazelleWarnings.AcceptOnMatch   = false
-
-log4perl.filter.NetworkErrors                   = Log::Log4perl::Filter::StringMatch
-log4perl.filter.NetworkErrors.StringToMatch     = Timed out at
-log4perl.filter.NetworkErrors.AcceptOnMatch     = false
-
-log4perl.filter.UnicodeErrors                   = Log::Log4perl::Filter::StringMatch
-log4perl.filter.UnicodeErrors.StringToMatch     = does not map to Unicode
-log4perl.filter.UnicodeErrors.AcceptOnMatch     = false
-
-log4perl.filter.BadModule               = Log::Log4perl::Filter::StringMatch
-log4perl.filter.BadModule.StringToMatch = Bad module supplied
-log4perl.filter.BadModule.AcceptOnMatch = false
+log4perl.filter.WarningsFilter                 = Log::Log4perl::Filter::StringMatch
+log4perl.filter.WarningsFilter.StringToMatch   = failed to writev: -1 errno:32|Timed out at|does not map to Unicode|Bad module supplied
+log4perl.filter.WarningsFilter.AcceptOnMatch   = false
 
 log4perl.appender.OUTPUT                          = Log::Log4perl::Appender::Screen
 log4perl.appender.OUTPUT.stderr                   = 1
-log4perl.appender.OUTPUT.Filters                  = GazelleWarnings
-log4perl.appender.OUTPUT.Filters                  = NetworkErrors
-log4perl.appender.OUTPUT.Filters                  = UnicodeErrors
-log4perl.appender.OUTPUT.Filters                  = BadModule
+log4perl.appender.OUTPUT.Filter                   = WarningsFilter
 log4perl.appender.OUTPUT.layout                   = PatternLayout
 log4perl.appender.OUTPUT.layout.ConversionPattern = [%d] [%p] [%X{url}] %m%n
 
 log4perl.appender.SYSLOG                        = Log::Dispatch::Syslog
-log4perl.appender.SYSLOG.Filters                = GazelleWarnings
-log4perl.appender.SYSLOG.Filters                = NetworkErrors
+log4perl.appender.SYSLOG.Filter                 = WarningsFilter
 log4perl.appender.SYSLOG.ident                  = metacpan_web
 log4perl.appender.SYSLOG.facility               = local0
 log4perl.appender.SYSLOG.layout                 = Log::Log4perl::Layout::JSON