Parse input as numeric when a numeric comparison is requested

[acoffman]

In the advanced search, if a user enters a non-numeric value when requesting a numeric comparison, it will generate a (still safe but) invalid SQL statement which will cause an exception. (https://griffithlab-apps.airbrake.io/projects/285901/groups/2894318614931625648/notices/2894318613519076496)

Ideally we'd do more validation client side and server side and kick back a more user friendly error in this case, but as a stopgap this will at least ensure the prepared SQL is valid and no error will occur.

[coveralls]

Pull Request Test Coverage Report for Build 406415571

• 0 of 16 (0.0%) changed or added relevant lines in 1 file are covered.
• 36 unchanged lines in 23 files lost coverage.
• Overall coverage decreased (-0.008%) to 15.921%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
app/models/advanced_searches/base.rb	0	16	0.0%

Files with Coverage Reduction	New Missed Lines	%
app/controllers/genes_controller.rb	1	83.54%
app/models/comment.rb	1	63.64%
app/models/concerns/moderated.rb	1	74.24%
app/models/concerns/with_countable_enum.rb	1	90.0%
app/models/disease.rb	1	69.23%
app/models/drug.rb	1	56.25%
app/models/evidence_item.rb	1	81.63%
app/models/gene.rb	1	84.21%
app/models/notification.rb	1	62.5%
app/models/on_site_subscription.rb	1	40.0%

Totals
Change from base Build 399074882:	-0.008%
Covered Lines:	2111
Relevant Lines:	13259

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💛 - Coveralls

[susannasiebert]

I think we're missing is_equal (or whatever the equivalent is).