Adds `getLocalizedStrings` to PluginMeta.

* These strings will be passed to the plugin in the options.
* The strings will be present at the base of the javascript object
  * This ensures compatibility with the default WordPress html entity conversion.
Adds support for localized strings.

* The Localized strings are now passed to javascript.
* The options of the plugin are written in a nested, options object.
  * This has the added side-effect of being ignored by WordPress's html
    entity serialization.
  * ie:- An option's type information is no longer lost, a boolean from
    PHP is a boolean on the javascript object. No deserialization/parsing needed.
Updates changelog
Merges branch 'feature/add-localization-to-plugin-meta' into develop