Disable label submit button if any field is empty
Move label coffeescript from view to class
Add testcase for invalid color
Labels need to be valid on name
Validate label titel in project scope
Trigger an update of save button if user pressed a preview color
Do label validation for issues/merge requests API
Merge pull request #7465 from Razer6/better_label_color_validation

Better label color validation, fixes #7454