accept '+' as a valid symbol in unix path

Fixes: #153
Signed-off-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>

Fixes #154

Author: kofemann

patterns/grok-patterns

@@ -35,7 +35,7 @@ HOSTPORT %{IPORHOST}:%{POSINT}
 
 # paths
 PATH (?:%{UNIXPATH}|%{WINPATH})
-UNIXPATH (/([\w_%!$@:.,~-]+|\\.)*)+
+UNIXPATH (/([\w_%!$@:.,+~-]+|\\.)*)+
 TTY (?:/dev/(pts|tty([pq])?)(\w+)?/?(?:[0-9]+))
 WINPATH (?>[A-Za-z]+:|\\)(?:\\[^\\?*]*)+
 URIPROTO [A-Za-z]+(\+[A-Za-z+]+)?