Add command to kill stray mojo shell servers so we don't have to remember it

mojo/devtools/common/devtoolslib/http_server.py

Index: mojo/devtools/common/devtoolslib/http_server.py
diff --git a/mojo/devtools/common/devtoolslib/http_server.py b/mojo/devtools/common/devtoolslib/http_server.py
index 16c76a98d5189638e0dfcb3a8d454ac21a6fc691..acc73c61bbd805d4f996ac1eb3892acceb7f8600 100644
--- a/mojo/devtools/common/devtoolslib/http_server.py
+++ b/mojo/devtools/common/devtoolslib/http_server.py
@@ -222,7 +222,8 @@ def start_http_server(mappings, host_port=0):
     print 'Failed to start http server for %s on port %d: %s.' % (
         str(mappings), host_port, os.strerror(error_code))
     if error_code == errno.EADDRINUSE:
-      print ('  Run `fuser %d/tcp` to find out which process is using the port.'
+      print ('  Run `fuser %d/tcp` to find out which process is using the port;'
              % host_port)
+      print ('  or use `fuser -k %d/tcp` terminate it.' % host_port)

[ppi, 2015/08/12 09:29:54]

nit: drop 'use'

[etiennej, 2015/08/12 09:30:56]

Done.

     print '---'
     raise