do not error if file is not there

unix_setup.sh

@@ -44,7 +44,7 @@ ext_jar_filepath=$PWD/autopsy/modules/ext/sleuthkit-postgresql-$TSK_VERSION.jar;
 if [ -f "$sleuthkit_jar_filepath" ]; then
 	echo "$sleuthkit_jar_filepath found"
 	echo "Copying into the Autopsy directory"
-    	rm $ext_jar_filepath;
+    	rm -f $ext_jar_filepath;
     	if [ "$?" -gt 0 ]; then  #checking if remove operation failed
         	echo "exiting .."
         	exit 1