Bail early from isns_init if addr is not set

If addr is not set, don't wait for the getaddrinfo to fail but exit early.
This prevents a weird-looking log message from being printed.

Signed-off-by: Andy Grover <agrover@redhat.com>
Use multiple gotos to handle possible error paths in main()

Clean up resources in the reverse order that they are allocated, and
use multiple goto labels so that each potential error cleans up only
the resources allocated at the time of failure.

Signed-off-by: Andy Grover <agrover@redhat.com>
Merge pull request #18 from agrover/init-error-handling

Initialization error handling