Support PythonQt wrapping of ctkDICOMDatabase

It seems PythonQt will only wrap classes that include an
optional parent argument to the constructor.  The hint for this
was in "./CTK-build/Libs/DICOM/Core/ctkScriptWrapPythonQt_Light_log.txt"
and "CTK-build/Libs/DICOM/Core/ctkMacroWrapPythonQt_log.txt"

Libs/DICOM/Core/ctkDICOMDatabase.cpp

@@ -133,7 +133,7 @@ ctkDICOMDatabase::ctkDICOMDatabase(QString databaseFile)
   d->init(databaseFile);
 }
 
-ctkDICOMDatabase::ctkDICOMDatabase()
+ctkDICOMDatabase::ctkDICOMDatabase(QObject* parent)
    : d_ptr(new ctkDICOMDatabasePrivate(*this))
 {
 }

Libs/DICOM/Core/ctkDICOMDatabase.h

@@ -34,7 +34,7 @@ class CTK_DICOM_CORE_EXPORT ctkDICOMDatabase : public QObject
 {
   Q_OBJECT
 public:
-  explicit ctkDICOMDatabase();
+  explicit ctkDICOMDatabase(QObject *parent = 0);
   explicit ctkDICOMDatabase(QString databaseFile);
   virtual ~ctkDICOMDatabase();