Moved tests directory to its own root.

When into odreex/tests directory, run:
    - make test : compiles test.cc, does not use ANSI coloured output.
    - make ctest: compiles test.cc, uses ANSI coloured output.
Some initial tests for odreex::ample::vector.

Tests using the testing framework for template metaprogramming constructs for
the newly introduced odreex::ample::vector.