Added vtd-xml for fast xml processing.
Cant find it on maven repo, so please run:

mvn install:install-file  -Dfile=vtd-xml.jar \
                          -DgroupId=com.ximpleware \
                          -DartifactId=vtd-xml \
                          -Dversion=2.11 \
                          -Dpackaging=jar \
                          -DgeneratePom=true
Added setters and JsonIgnore where appropriate.
Merge branch 'master' of https://github.com/agmip/translator-apsim

Conflicts:
	src/main/java/org/agmip/translators/apsim/core/SoilLayer.java