Universal Forwarder Support

[dmuth]

Since Splunk 8.0 has added to the Universal Forwarder a bit, I should add in support for a Universal Forwarder, specifically:

• A separate Docker Image (may need to build parallel to splunk-lab-core)
• A separate docker-compose.yml file that loads both Splunk Lab and the UF
• A separate starting script which will download a docker-compose.yml and have the UF read from logs/ and forwarded to Splunk.