[#1832] Use unique temporary folders.

Problem description
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This branch add support for unique temporary folders by using the latest empirical package.


Changes description
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Update brink and fix tests.

This also include a small cleanup for helper code and reduce duplicate setup in tests.

On unix all accounts are using the /tmp folder.

On WIndows, the default temp folder is in USER\Local Data\Temp... this is good as long as we don't use impersonation. The impersonated OTHER_USER don't have access to USER\Local Data\Temp.
As a quick hack I switched to c:\temp but we should fix this in ticket https://trac.chevah.com:10443/ticket/930


How to try and test the changes
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reviewers @alibotean 

check that changes make sense.