Make OS echo example Windows-compatible

IPython/testing/plugin/test_exampleip.txt

@@ -1,30 +1,30 b''
 =================================
  Tests in example form - IPython
 =================================
 
 You can write text files with examples that use IPython prompts (as long as you
 use the nose ipython doctest plugin), but you can not mix and match prompt
 styles in a single file.  That is, you either use all ``>>>`` prompts or all
 IPython-style prompts.  Your test suite *can* have both types, you just need to
 put each type of example in a separate. Using IPython prompts, you can paste
 directly from your session::
 
     In [5]: s="Hello World"
 
     In [6]: s.upper()
     Out[6]: 'HELLO WORLD'
 
 Another example::
 
     In [8]: 1+3
     Out[8]: 4
 
 Just like in IPython docstrings, you can use all IPython syntax and features::
 
-    In [9]: !echo "hello"
+    In [9]: !echo hello
     hello
 
     In [10]: a='hi'
 
     In [11]: !echo $a
     hi