Fix to run on Windows platform.

Removes pty module dependency. Because pty module
is unavailable on Windows platform.

When pty module is used on Windows platform, ImportError occurs below.

<pre>
Traceback (most recent call last):
  File "C:\Python27\lib\runpy.py", line 162, in _run_module_as_main
    "__main__", fname, loader, pkg_name)
  File "C:\Python27\lib\runpy.py", line 72, in _run_code
    exec code in run_globals
  File "C:\Python27\Scripts\sphinx-autobuild.exe\__main__.py", line 5, in &lt;modul
e&gt;
  File "C:\Python27\lib\site-packages\sphinx_autobuild\__init__.py", line 13, in
 &lt;module&gt;
    import pty
  File "C:\Python27\lib\pty.py", line 11, in &lt;module&gt;
    import tty
  File "C:\Python27\lib\tty.py", line 5, in &lt;module&gt;
    from termios import *
ImportError: No module named termios 
</pre>