Replace azure-storage-blob with libcloud

[c-w]

@adamsclafani tagging you as a reviewer on this pull request since it's related to your Celery refactor. This pull request replaces the azure-storage-blob library with apache-libcloud such that we can replace the Azure-based storage with the file-system for local development.

@laura-barluzzi tagging you as a reviewer for general feedback.

[codecov-io]

Codecov Report

Merging #47 into master will increase coverage by 0.37%.
The diff coverage is 97.36%.

@@            Coverage Diff             @@
##           master      #47      +/-   ##
==========================================
+ Coverage   91.44%   91.82%   +0.37%     
==========================================
  Files          24       24              
  Lines         830      844      +14     
==========================================
+ Hits          759      775      +16     
+ Misses         71       69       -2

Impacted Files	Coverage Δ
opwen_email_server/config.py	100% <100%> (ø)	⬆️
opwen_email_server/utils/temporary.py	100% <100%> (ø)	⬆️
opwen_email_server/services/storage.py	97.5% <96.96%> (+2.21%)	⬆️

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