Added ShiroSecurityConstraints to be able to have more than one security constraint on a Page.

For example:
If some edit page is only allowed in case the user is Authenticated (remembered users will have to login again)

@ShiroSecurityConstraints({
		@ShiroSecurityConstraint(constraint = ShiroConstraint.HasPermission, value = "editPermission"),
		@ShiroSecurityConstraint(constraint = ShiroConstraint.IsAuthenticated)}
)
Merge pull request #202 from brampouwelse/master

Allow multiple ShiroSecurityConstraints on a single page