Removes files in test/ and the .travis.yml from the npm registry
to make the package a bit smaller

Worktree's `.git` file contains absolute path to repository.
`path.join` incorrectly concatenates `/path/to/worktree`
with `/path/to/real/.git/worktrees/worktree` to
`/path/to/worktree/path/to/real/.git/worktrees/worktree`
instead of simple `/path/to/real/...`

Using `path.resolve` instead of `path.join` resolves this problem
while relative paths of submodules still works correctly.

* Update to handle failed prepare-commit-msg

* Added more accurate error message for `prepare-commit-msg` hook

* fix coding style to match standardjs.

0.14