Order independent kwargs handling during cache key calculation

[levitation]

Related to issue #132

Added sorting of kwargs so that changing the ordering will not invalidate the cache.
Added test for this feature.

Note: The keyword arguments are sorted only for cache key calculation. The actual function is still called with unordered arguments. The rationale for the latter is that if somebody is debugging their code then they might be confused if the arguments they see as their function input are in a different order than expected.

[shaypal5]

Nice! I've read the code and test - looks good. The tests are now running. Let's wait and make sure they all pass.

[levitation]

There are some test errors, but I do not quite understand them. Some are permission errors. Some tests failed in my computer even with unmodified code.

As far as I can tell, my modifications did not introduce new errors - tests that succeeded before, succeeded after modifications as well.

[levitation]

I see there is some blank line at the end of file formatting error. I will try to adjust that.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (b453aa5) 100.00% compared to head (1f44781) 100.00%.

Additional details and impacted files

@@            Coverage Diff            @@
##            master      #133   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            5         5           
  Lines          508       510    +2     
  Branches        88        88           
=========================================
+ Hits           508       510    +2     

Files	Coverage Δ
cachier/core.py	100.00% <100.00%> (ø)

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[levitation]

Looks like the "blank line at the end of file" formatting failure is fixed now.

The remaining test failures seem to be related to some connection error. I guess that is something I cannot control.

[shaypal5]

Please see PR #134 .

All tests pass when testing an actual MongoDB server, but test coverage dropped under a 100%.

See details in codecov:
https://app.codecov.io/gh/python-cachier/cachier/pull/134/indirect-changes

Please add a test to cover these lines.

@levitation