Update source /bin/agent commands to function like deb & redhat versions
Update source /bin/agent
Update source agent
Merge branch 'master' into source-agent-update
Update source agent
Update source agent init script to give more standard exit codes
Merge branch 'master' into source-agent-update

Conflicts:
	packaging/datadog-agent/source/agent
Fix logic in source init.d script
Merge pull request #513 from DataDog/source-agent-update

Update source /bin/agent commands to function like deb & redhat versions.
1. Exit codes are more standard now (for example, trying to stop when already stopped will return 0)
2. Fix a bug where every command would start the Agent before executing.