Add language selectors to main menu

[juangallostra]

The language options are currently only shown in the footer of each page. They should also be added to the top right corner of the main menu shown in each page.

[asantacreu]

Language selector has been replaced with a dropdown element, making it easier to move now.

[asantacreu]

Desing is needed as per how to show Language selector in Main menu for smartphones.