Do not display readonly translatable fields in the translate dialog
add standard files
[FIX] image urls
[FIX] flake8
[FIX] adapt to change in maintainer-tools
[IMP] Sandy's suggestions
Update .travis.yml
Merge pull request #13 from hbrunn/7.0_flake8

[ADD] standard files, flake8
Merge pull request #4 from guewen/web_translate_dialog-no-readonly

[IMP] do not display readonly translatable fields in the translate dialog