SHA256 Config Generator and CSS/Doc Improvements

[caronc]

Description:

Related issue (if applicable): refs #102

This is just a small PR with various changes:

• clean up some documentation - provided examples for curl from the API website
• dark mode improvements
• Added new configuration generator based on sha256 strings to allow people to generate more obfuscated configurations that can be exposed to the internet easier without being guessed.
• default configuration remains at apprise, but added a global variable APPRISE_DEFAULT_CONFIG_ID can be specified to over-ride this value if one wants.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.23%. Comparing base (46d9533) to head (c27bc31).
Report is 45 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #151      +/-   ##
==========================================
+ Coverage   95.16%   95.23%   +0.07%     
==========================================
  Files           7        7              
  Lines         703      714      +11     
==========================================
+ Hits          669      680      +11     
  Misses         34       34              

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