ENH: Added iohub as a submodule to psychopy: pyschopy.iohub. Please see notes.

+ psychopy now has an iohub sub module, psychopy.iohub
+ put the iohub examples in the demo/coder folder, in a dir called
'iohub'
- There are a couple issues I need to fix, but should allow for testing
kb and mouse on all platforms (I have only tested on windows so far)
- the 3-4 issues are on the iohub github bug tracker, all are tagged
with 'psychopy.iohub'  tag
- the one that bugs me the most is that in all the demo's I had to use
from psychopy.iohub import x,y,z . If I used from psychopy import iohub,
then from iohub import x,y,z, I get an import error saying there is no
module called iohub.