move from RUnit to Test::Unit.
removed Tests method calls, which is unnecessary by using Test::Unit.
Merge branch 'feature/move_to_test_unit' into develop
fix unit tests.
ruby 1.9.3.
Merge branch 'feature/sample_to_unit_tests' into develop
fix test__parcent for finite-group.
use 'test-unit' gem, by bundler.
remove .DS_Store from the repo.
fix installer for Ruby later 1.9.
use Test::Unit rather than original test framework.
fix indentations.
Merge branch 'feature/use_test_unit_on_all_tests' into develop
separate list tests from unit tests, because they look like
performance tests.
suppress messages in unit testing.
fix installer.
literal like 1/2r is not available in 1.9.3.
Merge branch 'release/20141226_release_01'