import trades from bitcoin.de via API

fixes #15

apps/transactions/templates/add.html

@@ -28,6 +28,13 @@
 	</div>
 	</div>
 
+	<div class="form-group row">
+	<label class="col-sm-2 col-form-label">Trade ID:</label>
+	<div class="col-sm-4">
+	  {{ form.trade_id }}
+	</div>
+	</div>
+
 	<div class="form-group row">
 	<label class="col-sm-2 col-form-label">Crypto Currency:</label>
 	<div class="col-sm-4">