[Style] Check db_creator.py for consistent style

[samgdotson]

The db_creator file should be checked for consistent style. For example, some functions that depend on regions will loop through tech.regions rather than the keys of the particular parameter.

# this will break if the place key doesn't exist.
for tech in tech_list:
    for place in tech.regions:
        data = tech.max_capacity[place]

However, not all technologies have data for ALL places. I.e. Place 1 might have a capacity limit, but Place 2 does not. In which case, trying to call tech.max_capacity[place] would break the database creation. In some cases, there is a try/except block that attempts to access the data if it exists, otherwise it skips. There is an easier way to do this however, and that is to loop through the keys of the dictionary tech.max_capacity.

# This is guaranteed to work without a try/except.
for tech in tech_list:
    for place in list(tech.max_capacity.keys()):
        data = tech.max_capacity[place]

That is one example where code should be made consistent throughout the module. There are sure to be others.

This issue should be resolved using Open Development practices.