Set tab language according to current language

The language for tabs is currently always the default language.

Authors are however allowed to set their own language using extensions such as Backend Language Switcher
This fix takes the base Symphony language and uses it for tab selection.
Merge pull request #7 from jonmifsud/patch-1

Set tab language according to current language
Added CRUD operations for translation data.xml files
Added delete-link
Some small fixes in delete-functionality
Merge pull request #8 from kanduvisla/master

I've got your CRUD right here! thanks @kanduvisla
Fixes a bug where you can't change the handle of a page once the pages translation is deleted
Merge pull request #9 from kanduvisla/master

Can't change page handle when page translation is deleted
Portuguese language and little label fix for context.
Merge pull request #10 from marciotoledo/master

Portuguese language and little label fix for context. thanks @marciotoledo