Don't throw an exception for files with only property changes.

Don't throw an exception for files with only property changes.

R= maruel

[Mark Larson, 2009-05-02 22:02:40]

A file with only property changes has the following status xml:

<entry
   path="browser\plugin_process_host.h">
<wc-status
   props="modified"
   item="normal"
   revision="15144">
<commit
   revision="14778">
<author>mal@chromium.org</author>
<date>2009-04-28T20:53:56.146253Z</date>
</commit>
</wc-status>
</entry>

When item='normal', gcl throws an error on line 165:

163    if xml_item_status in status_letter:
164      statuses[0] = status_letter[xml_item_status]
165    else:
166      raise Exception('Unknown item status "%s"; please implement me!' %
167                      xml_item_status)

I've added 'normal' as a valid xml_item_status.

[Mark Larson, 2009-05-02 22:10:10]

I already had this file open, so I 
  -- added 'missing' for '!'
  -- alphabetized the dictionary

[M-A Ruel, 2009-05-03 00:15:01]

lgtm but you'll need to switch your check out first to be able to commit. Note
that I'm moving this code to gclient.py to remove duplication, I'll make sure to
get it right.