sanic#1480 Allow negative int/number in path

[endafarrell]

I would like to be able to use possibly negative int and number values in routes.

This passes tests in:

• python 3.5.6; with two skips in test_app.py
• 3.6.8; also with two skips in test_app.py; and;
• 3.7.2 without any skips.

I've rerun make beautify on my newly added tests.

[codecov]

Codecov Report

Merging #1481 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1481   +/-   ##
=======================================
  Coverage   91.44%   91.44%           
=======================================
  Files          17       17           
  Lines        1730     1730           
  Branches      328      328           
=======================================
  Hits         1582     1582           
  Misses        123      123           
  Partials       25       25

Impacted Files	Coverage Δ
sanic/router.py	95.89% <ø> (ø)	⬆️

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[sjsadowski]

I'm okay with this and generally controversial changes get a fair bit of discussion. Given that it's gone a week without a peep, I'm going to approve and merge.