add arrow images to be compatible with django-treemenus
readme-update
Merge pull request #61 from iElectric/treemenus-compatibility

add arrow images to be compatible with django-treemenus
master to 2.4.0
Merge branch 'stable/2.4.x'
Merge branch 'stable/2.4.x'
Merge branch 'stable/2.4.x'
Merge branch 'stable/2.4.x'
Merge branch 'stable/2.4.x'
updated dev–version to 2.4.5