Linkify URLish modal values for event and client data.

This replaces URLs with HTML markup to linkify event and client values.  This is helpful for specifying client URLs (metrics, logstreams, etc) and event data (playbook, relevant metrics, etc).

Screenshot:
https://www.evernote.com/shard/s213/res/f6234bec-c11e-4a48-ab55-6474fd271980