MAINT: bumpy minimum NumPy required to 1.13.3

[tylerjereddy]

Fixes #2272

I adjusted the minimum required NumPy version to 1.13.3 for the relevant machinery I could find specifying 1.10.4 using git grep on our code base, but I did this quickly so we'll see what CI says.

I added a CHANGELOG entry too--one thought that occurred to me that is that people who put in review effort might not get acknowledged in that log, but that's a debate for another time maybe.

Also perhaps for another time, given current bandwidth, is establishing a clearer policy on major dependency version bumps, as noted in linked issue I think.

[tylerjereddy]

Can't remember if we have different build-time (i.e., numpy-distutils) vs. runtime NumPy version requirements, but maybe having them the same is less confusing anyway.

[codecov]

Codecov Report

Merging #2283 into develop will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop    #2283   +/-   ##
========================================
  Coverage    89.66%   89.66%           
========================================
  Files          172      172           
  Lines        21398    21398           
  Branches      2785     2785           
========================================
  Hits         19186    19186           
  Misses        1616     1616           
  Partials       596      596

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