Reset hashbang on the resulting binary
More work on Py3 compatibility

OpenCV 3 is required to use Python3 with OpenCV.  This must be
compiled from the source for now, and more information as to how
to do that will come later.

OpenCV 3 removes the `cv2.cv` and `cv` compatibility modules,
leaving just `cv2` to be used.  A few imports in `_ocv.py` had to
be reworked to account for this, but the impact for that was
minimal.

Python 3 removes implicit relative imports, which were being used
by the scripts loader.  In order to fix this, a few breaking
changes had to be made, specifically involving the loader and the
function to retrieve all possible scripts.

The loader had to be reworked to take in either a full path to the
module, or the individual script name (in order to maintain
backwards compatibility).  This required modifying the `__import__`
statement to correctly load the specific module when given a full
path.

The function to get the scripts list was refactored to make it
easier to read and understand.  It also now returns the full path
to the script, instead of the script name which it previously
returned.  The module name is grabbed from the current file, which
requires the loaders to remain in the `__init__.py` file.  Moving
them out of the file will require minimal adjustment to how the
current module is grabbed and should not be a problem in the
future.