Return nonzero exit codes on init function failure

Addresses #40

The Debian policy is vague on "proper" exit codes, many times
going against the LSB.  See http://wiki.debian.org/LSBInitScripts
for reference.  This commit goes with the LSB to at least return
nonzero exit codes on start/stop/reload/restart functions.
Short circuit start if runner is already running
Merge pull request #51 from basho/jem-deb-exit-codes

Return nonzero exit codes on init function failure