Allow assigment of Local repository per Parallel Build Queue

When building project using parallel queues, the few firsts builds always fails dues to dependencies error.
This seem to be caused by a concurrency issues between all maven instance and their shared repository.

Having the possibility to define a local repository per built queue, rather that per group would more likely solve this problem.

There's no warranty that 2 groups won't be using the same repository, when building in parallel, except by defining a different repository per single group, which is a waste of space. Moving the repository to the queue level would ensure that every single compilation has its one repository.