Add context variable to module IDs

[gregraka]

Hi,

I use Nebel to generate a new guide from an outline in a spreadsheet.

It would be nice if Nebel would add the context variable to the module IDs that it creates.

In the factory.py file, line 95, I found a way to achieve this:

filehandle.write('[id="' + metadata['ModuleID'] + '_{context}' + '"]\n')

If this change looks acceptable, I will submit a PR.

Please let me know.

Thanks,
--Greg Rakauskas