[FIX] use unique localstorage path when running phantomjs tests
this patch use a unique localstorage per test at al request. It could have used one localstorage per instance or even per module.
Merge pull request #785 from odoo-dev/saas-5-phantomjs-localstorage-fix-sle

[FIX] use unique localstorage path when running phantomjs tests