Consider including __version__ string to __init__.py

[dt-woods]

To assist with querying and validating the FEDEFL, it would be great to be able to do something like the following:

import fedelemflowlist 
print(fedelemflowlist.__version__)

[dt-woods]

Actually, what I want is the version of the FEDEFL list, not the Python package, as discussed in USEPA/ElectricityLCI#239 (reply in thread)