README update,  selective send section should use sendTo
add a non args constructor + extrac checks for serverURL
add a some javadoc to the buildUrl method
fix javadoc warnings and polish
add scm section
update developer section
fix formatting
Merge remote-tracking branch 'qmx/release_cleanups'
rename artifact to unified-push-java-client
renamed the tag name to unified-push-java-client
small typo
missing throw
remove unused param.
added missing variants param.
be specific on ids
missing getter for variants
added test case
moved to attributes map instead of fields
javadoc in-sync with the guide
refactor to have category, deviceType and variants on the correct level