setenv/getenv for framework uuid does not work w/ multiple fw test environment

[rlenferink]

By using the refactored launcher we can now start several frameworks from within one cpputest. This does collide with the usage of getenv/setenv for saving the framework uuid: after the first framework has set the uuid, every other starting framework will subsequently overwrite the uuid.

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Original creation date: 12/Nov/2015
Reporter: @bpetri