Add python shebangs to joinmarketd.py and wallet-tool.py

scripts/joinmarketd.py

@@ -1,3 +1,5 @@
+#! /usr/bin/env python
+
 import sys
 from twisted.internet import reactor
 from twisted.python.log import startLogging

scripts/wallet-tool.py

@@ -1,3 +1,4 @@
+#! /usr/bin/env python
 
 from jmbase import jmprint
 from jmclient import wallet_tool_main