Predefined ranges plugin do not support lang option

[bnisevic]

Describe the bug If a user wants the calendar to use different language than English this is done by using "lang" option. For example for German a user can have "lang": "de-AT". But this option is not supported in predefined ranges plugin. The default list of ranges is always in English and it comes from here https://github.com/wakirin/Litepicker/blob/master/src/plugins/ranges/index.js#L36-L41

To Reproduce Steps to reproduce the behavior: Example Litepicker object:

const picker = new Litepicker({
                                element: document.getElementById("litepicker"),
                                singleMode: false,
                                numberOfColumns: 2,
                                numberOfMonths: 2,
                                format: "DD.MM.YYYY",
                                autoApply: false,
                                buttonText: {"apply": "Übernehmen", "cancel": "Abbrechen"},
                                lang: "de-AT",
                                plugins: ['ranges'],
                                ranges: {
                                    position: 'left'
                                }
                            });

Expected behavior When "lang" option is used for another language this should also be applied to the predefined ranges plugin. Ranges names should be translated into the matching language.

[kl3sk]

Related https://github.com/wakirin/Litepicker/issues/223

[gago8910]

@wakirin could you review and merge request for custom labels?