Added meta to the uncountable array because "metum" is not a word.

[ErvinSabic]

Added 'meta' to uncountable so it doesn't turn it into metum, which is not a word at least not in the typical programming sense when people use the word "meta" like "meta data"

Tests all passed for this change.

There was an issue mentioned previously about this usage here - #67

Which leads to the rails convention this library is keen on following. But the convention is wrong, they just refuse to fix it because it will break existing applications as mentioned here - rails/rails#34914

Though I'm not sure why they don't just create some sort of a deprecation warning. (I'm not a rails developer)

Anyone else who is running into this issue in the meantime can create a inflector-rules.js file inside of their app/initializers/ directory (create it if it doesn't exist) and add the following code as a work-around.

import Inflector from 'ember-inflector';

export function initialize() {
  const inflector = Inflector.inflector;

  inflector.irregular('meta', 'meta');
}

export default {
  name: 'inflector-rules',
  initialize
};

[runspired]

meta is generally useful enough that probably we should do this if its not already a default; however, I think it might be? (its not)

note, i generally don't support the library adding its own rules #500 (review)

but meta is common enough it could be a good exception

[Techn1x]

Kind of related, If you're wondering how common it is, I've had this rule for half a decade in some apps
Inflector.inflector.uncountable('metadata')

EDIT: APIs should never have used english plurals for anything 😄