Rename numberRequired to minLength on ArrayInputView template

Rename numberRequired to minLength so it works with ampersand-array-input-view >= 2.0.0

https://github.com/AmpersandJS/ampersand-array-input-view/commit/8806fb08a206380f2097274a4ee4d978da029b4c#diff-8d634bcc6ae9fbf6b738528eb19bdd3aL66