Add the ability to add tags to an elasticsearch instance

The tags key is taken from the instance and each entry appended to the
already existing tags variable
Fix TypeError('NoneType') if tags is not set in configuration
remove unicode casting for syslog line, fixes #804

Causes a syslog emergency broadcast message to be displayed in certain
circumstances, like when using Python 2.6.5 on CentOS 5.x.

Since hostnames in unicode aren't valid, and we don't currently support
unicode host tags, this should be safe to remove.
Add the ability to add tags to an elasticsearch instance

The tags key is taken from the instance and each entry appended to the
already existing tags variable
Fix TypeError('NoneType') if tags is not set in configuration
Merge branch 'elasticsearch-tags' of https://github.com/indeedops/dd-agent into elasticsearch-tags

Conflicts:
	checks.d/elastic.py
	conf.d/elastic.yaml.example
Merge pull request #804 from DataDog/804_logging

Agent startup broadcasts 'emergency' message on RPM-based system
Add a WMI dependency for the DatadogAgent service

This is to prevent the case where the Agent can't start on a reboot
Merge branch 'master' of https://github.com/DataDog/dd-agent