Remove a whole bunch of deprecated storage backends

[jschneier]

Refs #202

[codecov-io]

Codecov Report

Merging #280 into master will increase coverage by 12.36%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           master     #280       +/-   ##
===========================================
+ Coverage   59.91%   72.28%   +12.36%     
===========================================
  Files          17       10        -7     
  Lines        1694     1371      -323     
===========================================
- Hits         1015      991       -24     
+ Misses        679      380      -299

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