Update Transfer.qml

1. Lack of consistency. Either all fields should have placeholder text or none of them should. 

2. I imagine this would be a slightly controversial edit, but is nevertheless correct, I feel. "Cost" is too non-specific to the new user, and it should be clearly identified that we are referring to transactional costs.

pages/Transfer.qml

@@ -87,7 +87,7 @@ Rectangle {
         // Amount input
         LineEdit {
             id: amountLine
-            placeholderText: qsTr("Amount...") + translationManager.emptyString
+            placeholderText: qsTr("") + translationManager.emptyString
             width: parent.width - 37 - 17
             validator: DoubleValidator {
                 bottom: 0.0
@@ -160,7 +160,7 @@ Rectangle {
         anchors.rightMargin: 17
         anchors.topMargin: 30
         fontSize: 14
-        text: qsTr("Cost")
+        text: qsTr("Transaction cost")
     }