Add a framework for detecting databases that need updating.

Put transaction from account_tx command in transaction application sequence.
CAUTION: This modifies your databases and will cause a delay on your next startup.

src/cpp/ripple/AcceptedLedger.h

@@ -31,6 +31,7 @@ public:
 	uint256 getTransactionID() const						{ return mTxn->getTransactionID(); }
 	TransactionType getTxnType() const						{ return mTxn->getTxnType(); }
 	TER getResult() const									{ return mResult; }
+	uint32 getTxnSeq() const								{ return mMeta->getIndex(); }
 
 	bool isApplied() const									{ return !!mMeta; }
 	int getIndex() const									{ return mMeta ? mMeta->getIndex() : 0; }