Merge branch 'implicit_storage_no_exception_on_release' into 'master'

Make releasing an implicit storage resources a no-op instead of exception.

Corrects Issue #16.

See merge request !62

vtkm/cont/StorageImplicit.h

@@ -99,7 +99,6 @@ public:
   VTKM_CONT_EXPORT
   void ReleaseResources()
   {
-    throw vtkm::cont::ErrorControlBadValue("Implicit arrays are read-only.");
   }
 
 private:

vtkm/cont/testing/UnitTestStorageImplicit.cxx

@@ -95,13 +95,9 @@ struct TemplatedTests
     }
     catch(vtkm::cont::ErrorControlBadValue) {}
 
-    try
-    {
-      arrayStorage.ReleaseResources();
-      VTKM_TEST_ASSERT(true==false,
-                       "Can't Release an implicit array");
-    }
-    catch(vtkm::cont::ErrorControlBadValue) {}
+    //verify that calling ReleaseResources doesn't throw an exception
+    arrayStorage.ReleaseResources();
+
   }
 
   void BasicAccess()