Add messaging and tests around the new Anaconda TOS

[ericdill]

See #14

[codecov]

Codecov Report

Merging #14 into master will increase coverage by 0.22%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #14      +/-   ##
==========================================
+ Coverage   90.36%   90.58%   +0.22%     
==========================================
  Files           3        3              
  Lines         415      425      +10     
==========================================
+ Hits          375      385      +10     
  Misses         40       40              

Impacted Files	Coverage Δ
conda_mirror/conda_mirror.py	89.02% <100.00%> (+0.35%)	⬆️

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