Update Maven dependencies. Also update plugin dependencies.

Add a prerequisite for Maven version.
The output of the Maven versions plugin is more readable
with a minimal Maven version and 3.1 looks like a reasonable base
version.

Exclude the Guava classes from the checkstyle scan as they don't
respect the new checkstyle rules but we want to keep them in sync
with Guava's original classes.
Update Maven dependencies and Maven plugins
Do not eat the exception message if it caught exception is the root exception
Support parsing devel versions like '9.4devel'
Merge pull request #91 from openwide-java/postgresql-devel-support

Rebased version of the patches of Mikko Tiihonen
[maven-release-plugin] prepare release pgjdbc-ng-0.4
[maven-release-plugin] prepare for next development iteration
Upgrade to Netty 4.0.23
Reference count the ThreadedHousekeeper nd shut it down when all connections are closed
Perform DriverManager.registerDriver in static initialization to ensure only one PGDriver is ever registered
Add custom PGDriver.cleanup call to perform, and wait for, complete shutdown of thread pools