Proper 'addr_spec' rule handling
Enhance JsSIP.Exceptions experience

-- Retrieve related useful information for each exception type
Give some love to "console.log|warn|info" messages missing the JsSIP class/module prefix.
Fix 'maddr' and 'method' URI parameters handling
Allow using a JsSIP.URI instance everywhere specting a destination.

Do not limit the target to be only a String.

Ie:
- ua.call(target,..)
- ua.sendMessage(target,..)
Fix stun_host grammar rule.
Merge branch 'master' into multi-browser