Merge remote-tracking branch 'upstream/master'
add parameter sourceDirectory with default value "src/main/dart"
build and use proper path to packages ($sourceDirectory instead of $basedir)
change outputDir to ${project.build.directory}/generated-sources/dwc and defaultPhase to GENERATE_SOURCES
remove support for packages in web projects (do one "package" per project)
set default value for parameter htmlFile to "web/index.html"
Merge pull request #34 from oliverlietz/master

more changes/fixes to get a proper build of a Dart web_ui project done