Fix inadvertent masking of errors when detecting jmx agent

The old code was catching *all* exceptions thrown by the code that detects whether
the jmx agent is already running in the VM, including errors that were intended
to be propagated to the caller.
Add convenience constructor to TimeStat
Update NEWS and CHANGES
Update to airbase 21
[maven-release-plugin] prepare release 0.89
[maven-release-plugin] prepare for next development iteration
Add abstract event client class
Update NEWS and CHANGES
[maven-release-plugin] prepare release 0.90
[maven-release-plugin] prepare for next development iteration
Do not include dependencies from zip files in lib dir

Zip files are not code and should not be included in the lib dir of an
assembly.  Also, transitive dependencies from zip files should not be
considered.
Update NEWS and CHANGES
[maven-release-plugin] prepare release 0.91
[maven-release-plugin] prepare for next development iteration