Add .gitignore
Add some unit tests

Since these all need a test ssh server to connect to,
you'll need to set some environment variables.

TEST_SSH2_HOSTNAME - Where to connect to
TEST_SSH2_PORT     - Port (default: 22)
TEST_SSH2_USER     - Login as (default: getenv('USER'))
TEST_SSH2_AUTH     - Mode of authentication ('none', 'password', 'agent')
TEST_SSH2_PASS     - Password to authenticate with
TEST_SSH2_TEMPDIR  - Where to store temporary files on the remote filesystem
                     (default: /tmp )