2.5.2 maintenance and dependencies

[MyPyDavid]

Description

• bump version of django-compressor to >=4.6 in f248e23.
  To prevent this error after update:

.../site-packages/compressor/finders.py", line 2, in <module>
    from compressor.storage import CompressorFileStorage
.../site-packages/compressor/storage.py", line 7, in <module>
    from django.core.files.storage import FileSystemStorage, get_storage_class
ImportError: cannot import name 'get_storage_class' from 'django.core.files.storage' (.../site-packages/django/core/files/storage/__init__.py)

[coveralls]

Coverage is 95.118% — 2.5.2/maintenance into 2.5.2/release. No base build found for 2.5.2/release.