Merge pull request #203 from origin/166-static-methods

Reduce "global_common" coupling by moving methods that could be
static onto "semantically-closer" py files.

Based on work initially made by @gmarmstrong on PR #166:

  - moves container-specific code out of global_common.py and into
    container.py
  - creates a util.py for static methods used through the whole app
  - move banner code from global_common onto cli.py given that it's
    only displayed there
  - updates tests to reflect these changes
  - move ocr_languages from global_common onto its own json file in
    share/ocr-languages.json to simplify global_common logic