Add capability to collect Storm logs via dmon-agent

[igabriel85]

Extend the capabilities of dmon-agent so that it can locate (if necessary) and then forward storm worker logs to dmon.
Implement method

GET -> /v1/node/stwork

Return the log of current storm worker.

Worker logs are usually located in ../apache-storm-0.9.3/logs. The ones with the format worker*.logs.

The logging directory can also be set from the config yaml file at:

storm.log.dir: /path/to/storm/logdir

or using the command line with:

-Dstorm.log.dir=/opt/storm/apache-storm-0.9.3/logs

[matejart]

When deploying the Storm worker nodes, will we need to add any steps additional to the current ones? Right now we basically register a Storm nimbus node with the DMon and request a restart of logstash. In the next releases, will we need to be careful to also prepare a dmon configuration for Storm workers?
Will the dmon-agent serve the logs or will some other log pushing mechanism exist?

[igabriel85]

I have just pushed our solution to collect to this repository. Details are in the I have just sent.
We only need to set the STORM_LOG environmental variable.

@matejart Do you set it when installing Storm?