fix(select): remove array render to support React <16

[austingreendev]

Closes #150

Description

Due to the ordering of our render() method in the SelectField component, we were unintentionally returning an array. This was breaking in React version < 16.

This PR updates the render method to now match the TextField component and remove the array.

Checklist

• 👌 design updates are Garden Designer approved (add the
  designer as a reviewer)
• 💅 view component styling is based on a Garden CSS
  component
• 🌐 Styleguidist demo is up-to-date (yarn start)
• ⬅️ renders as expected with reversed (RTL) direction
• 💂‍♂️ includes new unit and snapshot tests
• 📒 any new files are included in the packages src/index.js export
• 📝 tested in Chrome, Firefox, Safari, Edge, and IE11

[austingreendev]

@aravindet could you yarn add this locally into your codebase to ensure that this fixes the issue? I ran it locally in v15.4, but just want to double-check.

[coveralls]

Coverage remained the same at 96.039% when pulling 1291c58 on agreen/select-react-15 into fdd2b66 on master.

[aravindet]

(updated) Tested, works. 👍