Revert hard coded v1.7 jdk for darwin in karaf launch script introduced via KARAF-2921

As per KARAF-2921 The karaf script in jboss-fuse-full-6.2.1.redhat-107.zip is hard-coded to use Java 1.7 on Darwin/MacOS.

See line 201 of karaf script in bin directory:

201 if [ "x$JAVA_HOME" = "x" ] && [ "$darwin" = "true" ]; then
202 JAVA_HOME="$(/usr/libexec/java_home -v 1.7)"

expected:

either:

201 if [ "x$JAVA_HOME" = "x" ] && [ "$darwin" = "true" ]; then
202 JAVA_HOME="$(/usr/libexec/java_home -v 1.8)"

or:

201 if [ "x$JAVA_HOME" = "x" ] && [ "$darwin" = "true" ]; then
202 #JAVA_HOME="$(/usr/libexec/java_home -v)"