Update launcher for java 1.6 not 1.7
Improve code to detect java location on OS X.

Change-Id: Ic6b6adcbccc249344ea9ded28dcddad45ca87e50
Reviewed-on: http://gerrit.dmdirc.com/2758
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Greg Holmes <greg@dmdirc.com>