#54 CQPweb: internal licence system

[Andrew Hardie]

Certain corpora (eg BNC2104, TIGER) have online licence signup systems. It would be good if CQPweb could replicate their functionality internally to avoid people needing to wrestle with external signupm sites.

See note in code for update_corpus_access_statement(). The access statement system is a kind of half-arsed way of addressing this problem.

(Could this be done as a type of plugin?)