Update classpath settings to Java 7

The Mac Jarsigner plug-in requires Java 7 already due to the use of API
that is not availavle on Java 6. In order to avoid any confusion the
version is increased in the parent for all plug-ins.

Change-Id: I6d65cbab2b42f64442b4cc15745427c689a93324
Signed-off-by: Gunnar Wagenknecht <gunnar@wagenknecht.org>
Don't swallow server exceptions and improve logging.

Change-Id: I553a3e8f20fdfde8fea13af1d602de2d546ee560
Signed-off-by: Gunnar Wagenknecht <gunnar@wagenknecht.org>