Adding logstash plugin for Blueflood

This plugin is used to report metrics being tracked in logstash to an instance of blueflood
blueflood.rb is the plugin and the .conf files are logstash configs that are used to test out the plugin and also serve as use cases to demo our plugin

We have supported the following functionality:
1. Two types of metrics can be supplied. Well formed json or as a hash.
2. In case a hash is supplied, the plugin creates well formed json.
3. The plugin does an http post of the json to the blueflood instance 
4. TenantId and ttl need to be provided by the user.

Not supported - 
1. Passing creds in for cloud metric users

To review:
Is the documentation sufficient?

I think using the format field makes their intent more explicit. Also, it makes the logic easier to read especially for users.