Filter -SNAPSHOTs from resolved lower bound by default.

If you want to include -SNAPSHOTs in your lower bounds add

  -DincludeSnapshots

On your command line.
Handle 'null' upper ranges without writing 'null' into pom.xml
Refer to next release rather than SNAPSHOT.
Switched to use property= for consistency
Merge pull request #2 from talios/master

Filter -SNAPSHOTs from resolved lower bound by default.