Added configurable permission for creating folders

[Olicek]

Based on this discussion: #20

webimages:
    umask: 0777

[vojtech-dobes]

comma at the end of line please

[vysinsky]

Now please fixup it to only one commit:

git rebase HEAD~4 -i
Change 'pick' in 2nd to 4th commit to 'fixup' and save the change
git push -f

Edit: only the first commit should be here in the end

[Olicek]

Thanks a lot 👍! This is first time, i fixed up my mess in commits through this way

[vysinsky]

You're welcome!

[vojtech-dobes]

Can you please remove this? I don't want this in example configuration. But mention in readme would be nice.

[Olicek]

Finaly done :-)