Update image, config, docs, setup.
This MR does the following:
- Switches the image to one that includes a low-latency kernel and srsLTE 19.12.
- Adds an optional image-backed datastore which includes the srsLTE source.
- Switches the spectrum requests and configuration files to match new spectrum occupancy (DL channel now 2800 instead of 3400).
- Moves configuration into the profile repo to make it easier to maintain.
- Adds scripts to enable NAT forwarding, copy over config files, tune cpu performance, and fixup the X310 network interface at startup.
- Some documentation updates to match.