0.15.0 regression - Support negative numbers in the timestamp regular expression

[JBKahn]

This solves #662

Currently arrow does not allow you to pass in negative numbers for seconds relative to epoch when using strings. This patch is an attempt to fix this.

[JBKahn]

If this is a-ok could you cut a release for this?

[codecov-io]

Codecov Report

Merging #663 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master   #663   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           8      8           
  Lines        1536   1536           
  Branches      244    244           
=====================================
  Hits         1536   1536

Impacted Files	Coverage Δ
arrow/parser.py	100% <100%> (ø)	⬆️

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[systemcatch]

Thanks @JBKahn, we'll look this over then merge if it's all good. We're probably going to wait a little before releasing 0.15.1 in case any more obvious bugs arise. Is this one really messing you guys up?

[JBKahn]

Yeah, especially since a lot of apps don't lock down the version and we have lots of historical dates being passed into arrow.

[systemcatch]

Alright we'll speed things along then.

[jadchaar]

LGTM

[JBKahn]

Thanks, already had some issues with some places automatically picking up 0.15.0 if they din't lock the version and it was a sub-dependancy.