Set PROTOCOL_MIN to 1.0

Earlier protocol versions are used by 2.9.x clients of Electrum and
Electron Cash.  They all have the local daemon vulnerability, so
it seems a good time to phase out support for those clients.

Author: Neil Booth

server/controller.py

@@ -46,7 +46,7 @@ class Controller(ServerBase):
     '''
 
     CATCHING_UP, LISTENING, PAUSED, SHUTTING_DOWN = range(4)
-    PROTOCOL_MIN = '0.9'
+    PROTOCOL_MIN = '1.0'
     PROTOCOL_MAX = '1.2'
     VERSION = 'ElectrumX 1.4'