[FIXED JENKINS-20663] For now, go back to using ZipOutputStream from Ant that supports setting the filename encoding (present in java.util.zip only in Java 7+).

Correcting change made in #1176, which introduced an NPE, to restore original logic merely wrapped in a synchronized block.
Reproduced NPE in new functional test (original bug probably very hard to reproduce).

Signed-off-by: Oleg Nenashev <o.v.nenashev@gmail.com>

Signed-off-by: Oleg Nenashev <o.v.nenashev@gmail.com>

[FIXED JENKINS-14264] For logs >200Kb, just show two <t:task>s without nesting, for proper interoperability with the context menu.

[FIXED JENKINS-23191] f:radio is not databinding-aware and does not correctly handle multiple configuration sections unless you make it.