[reSIProcate] requestOffer in UAS_Accepted state

[Boris Rozinov]

Hi, guys

ServerInviteSession::provideOffer provides the
following treatment in UAS_Accepted state:
	case UAS_Accepted:
		// queue the offer to be sent after the ACK is
received
		transition(UAS_WaitingToOffer);
		mProposedLocalSdp = InviteSession::makeSdp(offer);
		mProposedEncryptionLevel = level;
		break;

I beleive that similar treatment (postponded request)
should be in case of requireOffer, but there is no 
ServerInviteSession::requestOffer and
InviteSession::requestOffer raise assert in this
state.
I've added the following code to
InviteSession::requestOffer	  
case UAS_Accepted:
		  // queue the offer to be sent after the ACK is
received
		  transition(WaitingToRequestOffer);
		  break;        
         
and then I hit the assertion at
InviteSession::dispatchWaitingToRequestOffer, that
checked that proposedSDP is present (which is
obviously bug).

Thanks