Provide configuration for manual launching of unit tests

This commit adds a .proverc configuration in lemonldap-* subdirectories

It allows you to run unit tests easily during development

    make clean && make
    cd lemonldap-ng-portal
    prove t/my-unit-test.t
    prove -v t/my-unit-test.t
    prove t/*.t

You'll get a nice colored output, plenty of details with '-v' (great is
you set logLevel to "debug" in the test), etc.