First fully working tests for the blocking_queue class that includes a
set of test suites and shared fixtures.

. modified:   Makefile
  . Added --log_level=test_suite the invocation of the blocking_queue_test binary
    to the test: target.

. modified:   include/blocking_queue.hpp
  . Added member:
    . const static int max_data_size_default = 5;
  . Refactored the set_size method to check that a positive int was passed in,
    otherwise a the default value (max_data_size_default) is used.

. modified:   include/blocking_queue_test.cpp
  . Completely refactored adding shared fixtures and fixture test suites