[jsx-pascal-case] Warns on single-character identifiers

[rayhatfield]

If I reference a component using a single character I get a PascalCase warning.

import C from 'common/components/Conditional';
<C ...>

[nkbt]

Yep would be nice to fix this one.

import H1 from '../../../UI/Elements/H1';
import A from '../../../UI/Elements/A';

const TermsOfService = () => (
  <span>
    <A className={css.url} href="/terms-of-service">Terms of Service</A>
  </span>
);