Add RegEx to get full size image and remove CU banner

[yakk0]

thanks for doing this! It's greatly helped my Ubooquity look great. I'm not a programmer, so I apologize for not doing this the "correct" way in GitHub, but I didn't want to risk screwing anything up. I hacked on comixology-to-ubooquity.py and worked out a RegEx that gets the full sized images and remove the Comixology Unlimited banner. Can this be added to the script?
The RegEx is '._[A-Z].*?(?=.jpg)'

I changed lines 295 and 296 from

            print(' - Downloading logo from: {!r}'.format(publisher_listing.logo_url))
            logo_data = get_file(session, publisher_listing.logo_url)

to

            logourl = (re.sub('\.\_[A-Z].*?(?=\.jpg)', '', publisher_listing.logo_url))
            print(' - Downloading logo from: {!r}'.format(logourl))
            logo_data = get_file(session, logourl)

Lines 308 and 309 from:

            print(' - Downloading header from: {!r}...'.format(publisher.header_url))
            header_data = get_file(session, publisher.header_url)

            headerurl = (re.sub('\.\_[A-Z].*?(?=\.jpg)', '', publisher.header_url))
            print(' - Downloading header from: {!r}...'.format(headerurl))
            header_data = get_file(session, headerurl)

and lines 354 and 355 from:

            print('  - Downloading logo from: {!r}'.format(series_listing.logo_url))
            series_logo_data = get_file(session, series_listing.logo_url)

to

            logourl = (re.sub('\.\_[A-Z].*?(?=\.jpg)', '', series_listing.logo_url))
            print('  - Downloading logo from: {!r}'.format(logourl))
            series_logo_data = get_file(session, logourl)

I'm sure this can be done a lot more elegantly than what I put together, but this works.