994 Add support for upper and lower

[dantownsend]

Resolves #994

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 65.90909% with 15 lines in your changes are missing coverage. Please review.

Project coverage is 91.91%. Comparing base (919983a) to head (8b155b5).
Report is 2 commits behind head on master.

Files	Patch %	Lines
piccolo/columns/column_types.py	63.63%	12 Missing ⚠️
piccolo/columns/base.py	77.77%	2 Missing ⚠️
piccolo/query/methods/select.py	50.00%	1 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##           master     #995      +/-   ##
==========================================
- Coverage   92.78%   91.91%   -0.88%     
==========================================
  Files         108      108              
  Lines        8182     8222      +40     
==========================================
- Hits         7592     7557      -35     
- Misses        590      665      +75     

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[dantownsend]

Using this instead: #996