Bump tarsnap version to 1.0.35
Temporarily disable failing test

tarsnap exists with 1 when you run tarsnap --version or --help. This
causes the test to fail each run. I'll talk to upstream about
changing this.
Provide an upgrade path for new versions.

This will upgrade tarsnap when the version attribute is bumped.
feather bin_path should not be an absolute path
Re-enable previously failing test.

I spoke with cperciva, and was able to convince him to change the
behavior of --version and --help. In the next release these will
no longer return 1.

In the mean time, he suggested using tarsnap --version || true, which
I didn't think of earlier.
Bump version to 0.1.7