Improvements for testing with external data.

- flexible AddTest() parameter parsing
- added parameter for
  - executable arguments
  - referenced external data files
  - diff data files
- gives fatal errors when a requirement for a specific wrapper or tester is not met

see Applications/CLI/Tests.cmake b/Applications/CLI/Tests.cmake
Fix travis build temporarily, tester test depends on wrapper test.
Allow for test executable which are not targets of ogs, e.g. mpirun.
Added target sync-data on envinf1 only.

This copies all file from ${CMAKE_SOURCE_DIR}/../ogs6-data to
/data/ogs/ogs6-data and then triggers a build on Jenkins which
syncs /data/ogs6-data to opengeosys.org
Added mpirun-wrapper.
Merge pull request #532 from endJunction/Cleanup

Cleanup
Merge branch 'bc' into develop
Merge branch 'test-improvements #529' into develop