Summary of changes:
1) IPython/core/compilerop.py: IronPython __future__ flags are non-standard,
Solution try/except; comment added
2) IPython/core/completer.py: __main__ was undefined, due to local mistake in
creating IronPython scope; removed this tweak
3) IPython/core/prompts.py: os.getuid() is not defined (IronPython bug; see:
https://mail.python.org/pipermail/ironpython-users/2014-February/016812.html)
4) IPython/lib/inputhook.py: ctypes SystemError; comment added
5) IPython/utils/process.py and IPython/utils/_process_cli.py: adds a
new _process_cli.py which would handle the processes under cli;
fixed os.pathsep
6) IPython/utils/io.py: devnull opened in append mode; changed to "w"
7) New issue: IPython/external/decorator/_decorator.py: IronPython doesn't
have _getframes, unless FullFrames is set to true; comment added
