Fixed broken paths for IPython > 1.x

In `ipython` > 1.x, the correct paths for `KernelManager` and `find_connection_file` are `IPython.kernel.manager.KernelManager` and `IPython.kernel.connect.find_connection_file` respectively.  See:

http://ipython.org/ipython-doc/2/api/generated/IPython.kernel.manager.html#module-IPython.kernel.manager
http://ipython.org/ipython-doc/2/api/generated/IPython.kernel.connect.html#module-IPython.kernel.connect

Let me know if this breaks for other versions of IPython, and I can write code to accommodate those.

Thanks so much for building this awesome plugin!