SSP-723 Compile-scoped deps for both PG and MSSQL drivers

So now shouldn't be any need to edit a uPortal POM depending on which
db platform you're targeting. Also, can override the specific dependency
coordinates for each driver via -D's on the command line:

  postgresql.groupId
  postgresql.artifactId
  postgresql.version
  mssql.groupId
  mssql.artifactId
  mssql.version