[FIX] allow resetting refused vacation requests
prevent the constraint to be recreated on update

This fixes https://github.com/odoo/odoo/issues/2112 at least for move
lines. If the constraint is not written exactly like that, the next time
we update the module OpenERP does not recognize it and drops and
recreates the constraint. This is dangerous, and takes a long time in a
big table.
Merge pull request #43 from lepistone/7.0-fix-move-line-constraint

prevent the constraint to be recreated on update
Merge pull request #21 from hbrunn/7.0-lp1303724

[FIX] hr_holidays: allow resetting refused vacation requests
[FIX] 'account' remove assert_file call when update database
[FIX] 'purchase' incorrect inheritance in partner view
[IMP] 'sale_stock' remove automatic warning when you sale product without stock available
Merge branch '7.0' of https://github.com/grap/OCB into 7.0