jigasi: don't make SIP proxy port and transport mandatory

jigasi/rootfs/defaults/sip-communicator.properties

@@ -8,10 +8,12 @@ net.java.sip.communicator.packetlogging.PACKET_LOGGING_ENABLED=false
 
 # SIP account
 net.java.sip.communicator.impl.protocol.sip.acc1=acc1
+{{ if and .Env.JIGASI_SIP_PORT .Env.JIGASI_SIP_TRANSPORT }}
 net.java.sip.communicator.impl.protocol.sip.acc1.PROXY_ADDRESS={{ .Env.JIGASI_SIP_SERVER }}
 net.java.sip.communicator.impl.protocol.sip.acc1.PROXY_AUTO_CONFIG=false
 net.java.sip.communicator.impl.protocol.sip.acc1.PROXY_PORT={{ .Env.JIGASI_SIP_PORT }}
 net.java.sip.communicator.impl.protocol.sip.acc1.PREFERRED_TRANSPORT={{ .Env.JIGASI_SIP_TRANSPORT }}
+{{ end }}
 net.java.sip.communicator.impl.protocol.sip.acc1.ACCOUNT_UID=SIP\:{{ .Env.JIGASI_SIP_URI }}
 net.java.sip.communicator.impl.protocol.sip.acc1.PASSWORD={{ .Env.JIGASI_SIP_PASSWORD | b64enc }}
 net.java.sip.communicator.impl.protocol.sip.acc1.PROTOCOL_NAME=SIP