Artifact creation improvements.
* java classes target 1.6 specified explicitly,
* hamcrest library removed from artifact assembly,
* sources and javadoc jars removed from artifact assembly,
* Jsoup library (lightweight HTML parser) added,
* transitivity removed from common-logging library (no more avalon in artifact!)
HTMP parsing fixed (see https://github.com/ThoughtWorksInc/go-maven-poller/issues/7)
* HTML content is treated in the same way, as XML content,
* HtmlResponseHandler removed; HtmlResponseParser added instead. It creates the same Content objects structure as XML unmarshalling,
* No qualifier handling in MavenVersion fixed (no ".null" appended),
* some tests for HTML parser and MavenVersion added,
* version increased to 0.3.1