release-version.sh: add --skip-deploy flag

We need this to release the ImageJ launcher, because its deployment is
more complicated. It needs to build on several architectures and then
deploy them all simultaneously. We already have our trusty Jenkins for
this, so let's skip the deploy when running the script, and instead tell
Jenkins to do the deploy from the tag after it is pushed.
pom-scijava: add ImageJ launcher version property

This is useful since the ImageJ launcher is now versioned separately
from ImageJ2.