Disable increment/decrement when min/max is hit

[kevinparkerson]

Makes the increment/decrement buttons disabled if the value is outside the allowed range and fixes an endless increment/decrement bug

Fixes #1644

Additional description

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CONTRIBUTOR checklist (do not remove)

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• Mocha, Jest (Storyshots), and components/component-docs.json CI tests pass (npm test).
• Tests have been added for new props to prevent regressions in the future. See readme.
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REVIEWER checklist (do not remove)

• TravisCI tests pass. This includes linting, Mocha, Jest, Storyshots, and components/component-docs.json tests.
• Tests have been added for new props to prevent regressions in the future. See readme.
• Review the appropriate Storybook stories. Open http://localhost:9001/.
• The Accessibility panel of each Storybook story has 0 violations (aXe). Open http://localhost:9001/.
• Review tests are passing in the browser. Open http://localhost:8001/.
• Review markup conforms to SLDS by looking at DOM snapshot strings.

Required only if there are markup / UX changes

• Add year-first date and commit SHA to last-slds-markup-review in package.json and push.
• Request a review of the deployed Heroku app by the Salesforce UX Accessibility Team.
• Add year-first review date, and commit SHA, last-accessibility-review, to package.json and push.
• While the contributor's branch is checked out, run npm run local-update within locally cloned site repo to confirm the site will function correctly at the next release.

[interactivellama]

This should be a last resort. Is there an alternative way to do this?

[interactivellama]

I do see that is is for uncontrolled components, so maybe there isn't an alternative. Let's at least put comments around it that says, we now it's bad. I'm thinking something like.

/*
 * Use of `this.forceUpdate` is an anti-pattern. This code only executes if this `input` element is uncontrolled which this library believes is an anti-pattern, also. This code is only present to allow for the edge case of uncontrolled use of an `input`.
 */

[interactivellama]

Looks good! @kevinparkerson I went ahead and added the commend and merged in.