Deploy and execute VDB throws exceptions if no server is defined

If no server is defined, deploy or execution of VDB causes an exception.

• rght click VDB: Modeling -> Deploy
  Unhandled event loop exception
  Caused by: java.lang.NullPointerException
  at org.teiid.designer.runtime.ui.actions.DeployVdbAction.checkForConnectedServer(DeployVdbAction.java:221)
  at org.teiid.designer.runtime.ui.actions.DeployVdbAction.run(DeployVdbAction.java:125)

• rght click VDB: Modeling -> Execute
  java.lang.NullPointerException
  at org.teiid.designer.runtime.ui.actions.ExecuteVDBAction.checkForConnectedServer(ExecuteVDBAction.java:127)
  at org.teiid.designer.runtime.ui.actions.ExecuteVDBAction.run(ExecuteVDBAction.java:95)

• execute VDB via Guides view:
  java.lang.NullPointerException
  at org.teiid.designer.runtime.ui.vdb.ExecuteVdbAction.checkForConnectedServer(ExecuteVdbAction.java:88)
  at org.teiid.designer.runtime.ui.vdb.ExecuteVdbAction.run(ExecuteVdbAction.java:60)
  at org.teiid.designer.advisor.ui.actions.AdvisorActionFactory.executeAction(AdvisorActionFactory.java:556)
  at org.teiid.designer.advisor.ui.views.guides.TeiidGuidesSection.launchGuidesAction(TeiidGuidesSection.java:252)
  at org.teiid.designer.advisor.ui.views.guides.TeiidGuidesSection.access$1(TeiidGuidesSection.java:244)
  at org.teiid.designer.advisor.ui.views.guides.TeiidGuidesSection$3.doubleClick(TeiidGuidesSection.java:153)