Add a basic test framework, borrowed from the framework used
by git.git. A shell script library (tests/test-lib.sh) helps
generate the fixtures, and simplifies the process of writing
test scripts. Tests can be run as a suite (via 'make test')
or individually (sh tests/t0000-config.sh). Results are aggregated
upon completion. Includes a detailed README.
A basic test of config file processing is part of this commit.
Signed-off-by: Emil Sit <sit@emilsit.net>