[T] Replace static var in tests with an outer def.

Running this test multiple times using
--gtest_repeat caused an error because of the
static modifier.

I would suggest not to use static in tests,
because the state of the test depends on execution
order.
Merge pull request #437 from endJunction/CorrectTestTimeStepping

[T] Replace static var in tests with an outer def.
Shuffle and repeat tests 3 times on Travis.
Disable MPI tests when shuffling.
Merge pull request #438 from bilke/travis-shuffle-repeat

Shuffle and repeat tests on Travis
First testing environment implementation.

See scripts/cmake/test/README.md for details.

Conflicts:
	SimpleTests/FemTests/CMakeLists.txt (ignored)
Time is just a shell function and FIND_PROGRAM has no REQUIRED arg.
Renamed 'test' target to 'gtest" and added 'ctest'-target.

These targets are renamed because CTest automatically generates a
target called ‚test‘ which cannot be modified.

make gtest - runs the unit tests
make ctest - runs upcoming executable tests
Testing stuff is not build by default target.

Build e.g. gtest-target to build and run the unit tests.
Added ExternalData-support for test data files.

See also http://docs.opengeosys.org/docs/devguide/testing/test-data
First test data example.
OGS-DATA_PATH is not needed anymore.
Renamed test target also on Travis.
Updated CMake on Travis to 2.8.12.2
Removed temporary test.
data target only depends on ctest target.
[T] Add back CMakes Test target to make all.