Add missing __init__.py files

 These files are needed so that existing import statements continue to
work elsewhere in the tree. For example:
 import models.aacgm   fails without the __init__.py file

This is just a little fallout of restructuring the rst related c code.

 Changes to be committed:
	new file:   models/aacgm/__init__.py
	new file:   pydarn/dmapio/__init__.py