Check for first-boot.json when registering a node for the first time

(I asked for this in IRC.)

I notice that all the knife bootstrap scripts have to manually add -j on the first call; I would also like this ability for my automated preseeded installed without having to deal with a first-boot script to call chef-client with -j option.

With some pointers I'd be willing to try a patch for this.

My thoughts on how this would work:

1) client.rb config value of "first_boot_json" being path to a json file.
2) if -j is on the command line this takes priority.
3) Anything else I'm missing

From CHEF-2359:

Chef no longer saves node data at the beginning of a chef run. This behavior shouldn't change, because it keeps half-built nodes from appearing in search results (and getting added to load balancers, monitoring systems, etc.). However, when bootstrapping a node fails, users find it confusing that they need to run chef with the -j /etc/chef/first-boot.json flag.

To resolve the problem, first-boot.json should be special in the following ways:

• It will be used automatically if it exists
• It will be moved out of the way (e.g., to first-boot.json.bak after a successful node save

It may also be desirable to have a default JSON attribs file for chef-solo, but that's a different matter.

CHEF-3025 added a '-j' option to knife bootstrap for providing JSON on the command line to be merged into the first-boot.json that we put the run list in and specify in the core bootstrap templates. This may help as a workaround, but a nice solution is still probably due.