bootstrap image: Add remote command execution script

In order to automate the complete bootstrap build process we need a
mechanism to control the second phase which builds the final packages
on the booted bootstrap Haiku. To avoid additional dependencies
(buildbot slave, ssh, rsh,...) we'd have to cross-build, there's now a
pair of simple python scripts that allows executing commands on a remote
machine. The server script (bootstrap_daemon.py) is added to the
bootstrap image and started automatically during the boot.

build/scripts/bootstrap_daemon.py

@@ -0,0 +1,61 @@
+#!/usr/bin/env python
+
+import socket
+import subprocess
+import sys
+
+
+address = '0.0.0.0'
+port = 4242
+
+
+def receiveExactly(connection, size):
+	data = '';
+	while size > 0:
+		dataReceived = connection.recv(size)
+		if not dataReceived:
+			raise EOFError()
+		data += dataReceived
+		size -= len(dataReceived)
+	return data
+
+
+def handleConnection(listenerSocket):
+	(controlConnection, controlAddress) = listenerSocket.accept()
+	(stdioConnection, stdioAddress) = listenerSocket.accept()
+	(stderrConnection, stderrAddress) = listenerSocket.accept()
+
+	print 'accepted client connections'
+
+	try:
+		commandLength = receiveExactly(controlConnection, 8)
+		commandToRun = receiveExactly(controlConnection, int(commandLength))
+
+		print 'received command: ' + commandToRun
+
+		exitCode = subprocess.call(commandToRun, stdin=stdioConnection,
+			stdout=stdioConnection, stderr=stderrConnection, shell=True)
+
+		controlConnection.send(str(exitCode))
+	finally:
+		controlConnection.close()
+		stdioConnection.close()
+		stderrConnection.close()
+
+	print 'client connections closed'
+
+
+listenerSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+listenerSocket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+
+try:
+	listenerSocket.bind((address, port))
+except socket.error, msg:
+	sys.exit('Failed to bind to %s port %d: %s' % (address, port, msg[1]))
+
+listenerSocket.listen(3)
+
+print 'started listening on adddress %s port %s' % (address, port)
+
+while True:
+	handleConnection(listenerSocket)