An integration test suite

This test suite uses cram to run integration tests through `/bin/sh`.
The tests are all high-level acceptance tests; they should work
regardless of the implemention code.

To run them, you must first install cram:

    sudo pip install cram

Then the `check` target will run them:

    make check

Failure output should be printed clearly to stdout, but in general: full
test output is in `test/test-suite.log` and output specific to a test
named `foo.t` is in `foo.t.log`.

Tests are now encouraged in `CONTRIBUTING.md` as part of the normal pull
request process.

This is a TAP-enabled test suite.