Generate separate surefire XMLs for each test suite

Previously the test cases of all test suites (=modules) were put in
one and the same surefire report XML thereby breaking the principle of
least astonishment and making post analysis harder.  Assume the
following layout:

    src/x.erl
    src/y.erl
    test/x_tests.erl
    test/y_tests.erl

The results for both x_tests and y_tests were written to only one
report grouped under either module x or y (seemingly randomly).

Now two reports, one for module x and one for y are generated.

0 files changed, 0 insertions, 0 deletions