shaclc: handle grammars copyright

[VladimirAlexiev]

In order to get to being a working group, the IP and copyright of material needs to be handled.

The different grammars are under different licenses or no license mentioned and have different copyright owners.
They are not under the W3C Software License.

This should be written down somewhere with attribution for copyright (README may be).

The Community Contributor License Agreement does not apply if the copyright owner isn't the one contributing the work.

One possibility is to to link to resources rather than copy them, then have a clearly labelled "snapshot" with date and explain this is to protect against link rot.

Originally posted by @afs in #49 (comment)

[jeswr]

FWIW the jison grammar I made is MIT licenced and I give permission for it to be used freely without attribution.