Simplify fixtures for testing
Run tests off fixtures

Most of the annoying issues people are running into have to do with reading off
of the file system. Our tests should cover file system issues, and now they do.

Includes a failing test for correct import sourcemap paths, which I'll fix in an
upcoming commit.
Remove gulpfile

Anything we were using the gulpfile to manually test we can/should now do in
test.js.
Merge pull request #105 from sindresorhus/rw/test-from-fixtures

Test from fixtures