When a bind is pending, no other operation should be allowed

If we issue a BindRequest, we should not be able to launch another request to the server using the same connection :

RFC 4511, chap 4.2.1 :
"After sending a BindRequest, clients MUST NOT send further LDAP PDUs
until receiving the BindResponse. Similarly, servers SHOULD NOT
process or respond to requests received while processing a
BindRequest."

Right now, the server accept other requests, which is wrong