AMQP-270 Fix Bundlor

Missing package in manifest - no support for explicit
package imports.

Update gradle bundlor plugin to a version that supports
explicit imports.
AMQP-281 Shut Down Timer in AMQP Appender

When using the AMQP log4j appender, it
can cause orphaned daemon threads when undeploying WARs.

Also, when exiting main() methods, apps should call
Log4jConfigurer.shutdownLogging(); in a finally block
to destroy() the connetion factory (releasing threads
used by the rabbit client).
AMQP-295 Fix Maven Version in Quick Start
AMQP-282 Log4j Appender - Configurable Charset

A charset is used when converting the message body
String to a byte[] to send to AMQP.

For backwards compatibility, the appender uses the
system charset by default, but now allows the charset
name to be specified in the log4j configuration...

log4j.appender.amqp.charset=UTF-8