[Mesh] update on building firmware

Hey y'all - I've been rummaging around the https://github.com/sudomesh/sudowrt-firm ware on and off the last couple of weeks. I found that I (and I assume others) could not reliably build our sudowrt firmware, and without firmware no peoplesopen, so I got motivated. Some observations / updates: - docker images are now being pushed from travis to docker hub daily or whenever a change occurs. This images contain a base build image that you can pull to your own environment. - I refactored some of the build scripts in an effort to separate the getting of resources (feeds etc.) from the actual building to reduce variability  - aside from pushing build images to docker hub, travis also attempt to create a firmware build, and gets terminated after about 40 min because of > 4MB of console output.  - the version of openwrt is now fixed to a specific commit hash (see ht tps://github.com/sudomesh/sudowrt- firmware/blob/master/openwrt_config/version): previously we were building off of HEAD, with all excitement associated to it. - I found out that during make (the actual building of the firmware), all sorts of dependencies are downloaded. Some of these dependencies are no longer available for the last openwrt release 15.05.1 (e.g., htt ps://github.com/sudomesh/sudowrt-firmware/issues/114).  - still working on creating a home node firmware build . . . Curious to hear your thoughts, -jorrit