UMS automTest: remove unrequired string initialization in fixtures

std::string default constructor already initialize strings as an empty one
UMS automTest: use C++ cast operators instead of unsafe C cast ones

* use const_cast<char*> instead of (char*)
* make vishnuClientTestConfigPath an immutable string to ensure
that the C string we use later will remain valid during our tests.
DIET -> Vishnu

Replaced DIET by Vishnu in the code and in some of the documentation files
Externalisation of request now possible, first example with the update with join that does not work the same for mysql and postgresql, so a map containing the request is stored
Fix for restore configuration
Fix with join update problems, all ums automtest are ok on postgre now
Add description of parameters to be replaced for requests
Remove useless variable
Add TODO + first try for a fix
Best way to pass tests is to remove the ones that don't work
Fix missing end of block
Change the test, was sometimes failing because the session was sometimes closed between the list and the reopen
Externalize all SQL requests from AuthAccount as an example on how it works for common requests
Comment cout
Comment why a line of code is unreachable
Add save/restore conf at beginning/end of test to stop filling the database with lots of users/machine when running tests
Comment an irrelevant test, will remove it later
Remove cout
add Sed and client configuration keys for ssl support
add config key for ssl use