[FIX] data dir when home is not a directory

Use site data dir instead of user data dir when user's home is not a directory.
Like system users created with /dev/null as home.

Stricter than before.
Merge pull request #1343 from vice/master

[FIX] data dir when home is not a directory
[IMP]sale,website_quote : move validity_date field from website_quote to sale. and display that field in quotation send by email as Expiration date.