Results 2 issues of Mauro Ciancio

In order to prevent serialization issues in clustered environments. Related to #75.

In `FacebookAuthUtils.groovy` (https://github.com/splix/grails-spring-security-facebook/blob/master/src/groovy/com/the6hours/grails/springsecurity/facebook/FacebookAuthUtils.groovy#L98 and https://github.com/splix/grails-spring-security-facebook/blob/master/src/groovy/com/the6hours/grails/springsecurity/facebook/FacebookAuthUtils.groovy#L136) requests are made to Facebook API. The connection has no timeout so the request thread can block forever (I've experienced this with other api's, not...