Bitcoin-Qt: massive header and cpp cleanup

- try to enforce the same style to all Qt related files
- remove unneeded includes from the files
- add missing Q_OBJECT, QT_BEGIN_NAMESPACE / QT_END_NAMESPACE
- prepares for a pull-req to include Qt5 compatibility

src/qt/bitcoinamountfield.h

@@ -13,7 +13,9 @@ QT_END_NAMESPACE
 class BitcoinAmountField: public QWidget
 {
     Q_OBJECT
+
     Q_PROPERTY(qint64 value READ value WRITE setValue NOTIFY textChanged USER true)
+
 public:
     explicit BitcoinAmountField(QWidget *parent = 0);
 
@@ -56,5 +58,4 @@ private slots:
 
 };
 
-
 #endif // BITCOINAMOUNTFIELD_H