MAVENHOME_CONFIG var in mvnlauncher script improperly handles two options at once

This variable sets:

-MAVENHOME_CONFIG=`echo "-Dclassworlds.conf=${MAVEN_HOME}/bin/m2.conf" "-Dmaven.home=${MAVEN_HOME}"`

We properly quote all other variables to avoid pitfalls like spaces, etc. Unfortunately, Bourne shell does not support arrays to this variable is passed as-is and spaces cannot be escaped. The command fails.
This variable needs to be replaced with one for ClassWorlds Conf file and Maven home is already present.

Windows command script properly handles spaces in the variables and passes to the java command.