Fix: Event identification regexp to include YYYY-MM format
Fix: Event identification regexp to include YYYY-MM format

When fetching Event by identification text, which could be either event
ID or slug, format 'YYYY-MM-text' was not correctly matched.  Both
'YYYY-MM-DD-text' and 'ID' worked correctly, though.

This is now fixed.  Fetching Event by ident now checks these 3 formats
(in this order):

* 'ID'

* 'YYYY-MM-****'

* 'YYYY-MM-DD-****'

wking/swc-amy,shapiromatron/amy,pbanaszkiewicz/amy,pbanaszkiewicz/amy,wking/swc-amy,swcarpentry/amy,vahtras/amy,swcarpentry/amy,wking/swc-amy,pbanaszkiewicz/amy,vahtras/amy,wking/swc-amy,shapiromatron/amy,swcarpentry/amy,shapiromatron/amy,vahtras/amy