Conflicts:
	htdocs/societe/document.php

Changelog & lang en_US for Skype module

FHenry-develop

Conflicts:
	htdocs/core/class/extrafields.class.php

fix : language

Task 157 : add a Skype button

missing trad

extrafields table 

Fix: Line was not added correctly
Fix: Missing message

that need a task to fix. This is not the case for a close thirdparty (a
close thirdparty is a regular status). However to have a bigger contrast
with thirdparty active, i set picto to statut5.png

language

Contining task 172