Create `bucket_list_tag`

[schloerke]

Fixes #20

Allows for bucket_lists to be made from sortable_js objects directly

[codecov-io]

Codecov Report

Merging #26 into master will increase coverage by 0.07%. The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #26      +/-   ##
==========================================
+ Coverage   94.11%   94.19%   +0.07%     
==========================================
  Files          10       10              
  Lines         221      224       +3     
==========================================
+ Hits          208      211       +3     
  Misses         13       13

Impacted Files	Coverage Δ
R/bucket_list.R	100% <100%> (ø)	:arrow_up:

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[schloerke]

Deferring until second release