Use browser locale when locale is not explicitly set

[StefanIvanov]

Description

When a locale is not explicitly set our components use the "en" locale, rather than checking for the browser locale and using it instead of the "en" one

Steps to reproduce

1. Create a calendar
2. Don't set an option for locale
3. Calendar shows with "en" locale

Result

"en" locale is used whenever the developer has not set a locale explicitly

Expected result

If no locale is set, the control should try to use the browser locale and only if this fails for some reason the locale should be set to "en"