Mark the Crowd tokens with an instance-specific prefix

Crowd is not able to handle nicely the situation where two sets of applications are managed by two Crowd instances, with related SSO domains (.subdomain.mycompany.com and .mycompany.com).

This leads to impossible login in the application with the more specific domain when logged in the the other application.

Since Crowd cannot get Cookie metadata from the browser, the solution would be to mark Crowd token with an instance specific prefix.