[cleanup] cleanup scripts/imagetransger.py
[cleanup] cleanup scripts/imagetransger.py

- use single quotes for string literals
- use str.format(...) instead of modulo for type specifier
  arguments
- remove preleading "u" from strings
- use "+" to concatenate strings in some cases

Change-Id: Iee0594ceefdca570585c2e933f385b6ba485fc6d

wikimedia/pywikibot-core,wikimedia/pywikibot-core,PersianWikipedia/pywikibot-core