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
Adding support for sending custom headers in the HTTP check.
Install expat xml parser dependency

Fixes #450
Release 3.8.0 for source install
Merge pull request #543 from DataDog/smartos-pkg-expat

Install expat xml parser dependency on SmartOS
add HDFS check using snakebite
add 'in_use' (percent used) gauge
Merge pull request #542 from tomduckering/master

Adding custom header support to http_check.
Fix postgresql.rollbacks metric and don't crash when tags are None.

postgresql.rollbacks metric was collecting the wrong data due to a typo.
chef-datadog 1.0.1 can create a tags entry with a None value, causing the
the agent to crash. This is now fixed.
Add optional response_time metric in tcp and http checks

Also remove trailing spaces
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.
Fix version checking in MySQL checks, fix #558

Also remove some trailing spaces
Replace agent in front-facing code with Agent