Added slf4j so we can log exceptions and allow users of this library
choose there preferredd logger.
Added logging to exceptions.
Merge branch 'master' of https://github.com/bsutton/CalDAVServlet-1.git

Conflicts:
	src/main/java/com/ricardolorenzo/network/http/caldav/method/COPY.java
	src/main/java/com/ricardolorenzo/network/http/caldav/method/DELETE.java
	src/main/java/com/ricardolorenzo/network/http/caldav/method/PROPPATCH.java
	src/main/java/com/ricardolorenzo/network/http/caldav/method/PUT.java