Enable process check on Windows

Fix #819
Merge branch 'master' of https://github.com/DataDog/dd-agent
Fix process check on windows
Add sudoers comment to postfix.yaml

since it's more likely to be read than the code.
Fix Cassandra link for travis
Merge branch 'master' of https://github.com/DataDog/dd-agent
Fix cassandra location
Skip Elastic search test for now

See #825
Merge branch 'master' of github.com:DataDog/dd-agent into statsd_buckets

Conflicts:
	.travis.yml