Updated POM to inherit dependencies from THREDDS project, bumped THREDDS version to 4.3.15

POM was updated to inherit dependencies form THREDDS project using dependency managment and import scope  with thredds-parent pom.   Some dependencies were modified to use groupId and artificatId consistent with those in thredds-parent pom.  This change will guarantee that ncSOS is compiled against the same jars used in THREDDS.  It also has the benefit that ncSOS will not introduce duplicate jars if a maven war overlay is used to inject nsSOS into to THREDDS.