[+]BO : add a flag ALL (ALL languages) for set a value to all languages

It duplicate the value to all language to set a numeric value esay to all language like (lenght, weight...). It's very simply for encode multilingual product features.
[*] BO : performance improvement on AdminInvoices loading time
// remove first li if $best_sellers == false
fix copy/paste for DB_PREFIX
Merge pull request #1146 from studiokiwik/sk-ps16x-001

[*] BO : performance improvement on AdminInvoices loading time
[-] MO : homeslider - fix wrong text position
// revert
Merge branch '1.6' of https://github.com/PrestaShop/PrestaShop into 1.6
// fixtures
// leave homefeatured on hook home
// small fix
Merge branch '1.6' of https://github.com/PrestaShop/PrestaShop into 1.6
[-] WS : Fix bug #PSCFV-11328 : Don't insert attribute image(s) id if no id to insert

There was an issue with the webservice where inserting an empty <images node_type="image"></images> tag would result in an error 500 when it was not needed.
// typo
[-] MO : homeslider - add on description click event
Merge pull request #1148 from adastier/patch-1

[-] WS : Fix bug #PSCFV-11328 : Don't insert attribute image(s) id if no...
// Fixed, cleaned and commented pagination
// Forecast colors
[-] CORE : Fix missing php self
// Adding blocklayered fixture to installation