Publish stackLicense files to IPFS

[oberstet]

Creating a new XBR Domain requires a stackLicense:

https://github.com/crossbario/xbr-protocol/blob/825d54c9e222582dfae60504f6827ed561dd1d49/contracts/XBRDomain.sol#L93

The license for the software stack running the domain. IPFS Multihash pointing to a JSON/YAML file signed by the project release key.

For now, we need to publish 3 files for stackLicense:

License	Description
„capacity license“	worker capacity (by maximum concurrent workers)
„usage license“	worker usage (by consumed monthly worker hours)
„free license“	limited, best-effort

[oberstet]

we need to coordinate/discuss/finalize with Alex which license files to publish, and add that publication at least as a Makefile target in the repo here (or other convenience scripting) ..