[*] Project : Add if defined to _PS_OVERRIDE_DIR_ constant
Merge pull request #1567 from xBorderie/1.6

[*] BO : Update indications in default e-mails.
Merge pull request #1564 from johnstyle/feature/patch-1

[*] Project : Add if defined to _PS_OVERRIDE_DIR_ constant
//added adminPatterns
Merge branch '1.6' of https://github.com/PrestaShop/PrestaShop into 1.6
[*] BO : Remove references to back-office screens in e-mails sent to the customer.