updated support list information

Corrected the information in the mailingList element to point to the new
protege-user support mailing list and also changed archive pointer to
Nabble.  The p4-feedback mailing list is obsolete.
added new "prepare-release" profile

Added a profiles section with a new profile called "prepare-release".
Moved the generation of the sources and javadoc JAR files and GPG
signing to this profile.  Only want to execute these when we're doing a
real release of this bundle, not when doing local development.  To use
this profile, type "mvn install -Pprepare-release".
upgrade to latest version of maven-gpg-plugin

Went from 1.4 to 1.5.  Note for Windows users - you need to specify the
passphrase on the command line, e.g., -Dgpg.passphrase=thephrase.  If
you left this out in 1.4, the plug-in would prompt you for the
passphrase.  In 1.5, the plug-in will sometimes hang if the passphrase
is not specified on the command line.  Don't know if this is specific to
Windows - did not test other platforms.
upgrade to latest version of maven-javadoc-plugin
removed obsolete files

No longer need the JAR files in the lib directory, which were used by
the old Ant build scripts.  Building with Maven now, so dependencies are
designated in the POM file.  Also deleted MANIFEST.MF since this is
auto-generated by Maven.
modified uri for pizza ontology

The old URI caused an UnloadableImportException in IRIMapperTest.  The
pizza ontology no longer exists at the old URI.