Fixed linter errors and reduces boilerplate code for error handling

[woehrl01]

This PR does some general cleanup.

• Fixing of general linter errors (unused variables, unneeded escaping in regex, missing , etc.)
• Typos in comments and readme
• Extended readme to include information about not supported device features.
• Removing of Macs .DS_Store files
• Replaces a JSON parsed from a string concatenation with a direct object creation
• Removing of duplicate method definitions to access properties.
• Reducing boilerplate code in KeyError handling by using a decorator
  • This one also allows an easier change of logic as discussed in Change error in case of value not found #52
  • I also added handling of IndexError to gracefully handle one of the errors mentioned in missing info on homeassistant #51

[woehrl01]

I'm more than happy to modify this PR to reflect the discussion in #52 . I'd suggest adding a exception type PyViCareNotSupported, what do you think @oischinger, @crazyfx1, @somm15 ?