Correct a few cases of address encoding.

There are certain RPCs where an address should be sent as the raw string
instead of the encoded bitcoin address since the RPC handler on the other
end expects "keys" instead of Bitcoin addresses.

For example, the multisignature RPCs addmultisigaddress and createmultisig
can work with pubkeys (compressed, uncompressed, or hybrid) as well as
Bitcoin addresses.

The original issue which prompted these changes was report by Paul Snow on
IRC.

notify.go

@@ -847,7 +847,7 @@ func (c *Client) NotifyReceivedAsync(addresses []btcutil.Address) FutureNotifyRe
 	// Convert addresses to strings.
 	addrs := make([]string, 0, len(addresses))
 	for _, addr := range addresses {
-		addrs = append(addrs, addr.EncodeAddress())
+		addrs = append(addrs, addr.String())
 	}
 	id := c.NextID()
 	cmd := btcws.NewNotifyReceivedCmd(id, addrs)
@@ -921,7 +921,7 @@ func (c *Client) RescanAsync(startHeight int32, addresses []btcutil.Address,
 	// Convert addresses to strings.
 	addrs := make([]string, 0, len(addresses))
 	for _, addr := range addresses {
-		addrs = append(addrs, addr.EncodeAddress())
+		addrs = append(addrs, addr.String())
 	}
 
 	// Convert outpoints.
@@ -996,7 +996,7 @@ func (c *Client) RescanEndHeightAsync(startHeight int32,
 	// Convert addresses to strings.
 	addrs := make([]string, 0, len(addresses))
 	for _, addr := range addresses {
-		addrs = append(addrs, addr.EncodeAddress())
+		addrs = append(addrs, addr.String())
 	}
 
 	// Convert outpoints.

rawtransactions.go

@@ -257,7 +257,7 @@ func (c *Client) CreateRawTransactionAsync(inputs []btcjson.TransactionInput,
 	id := c.NextID()
 	convertedAmts := make(map[string]int64, len(amounts))
 	for addr, amount := range amounts {
-		convertedAmts[addr.EncodeAddress()] = int64(amount)
+		convertedAmts[addr.String()] = int64(amount)
 	}
 	cmd, err := btcjson.NewCreateRawTransactionCmd(id, inputs, convertedAmts)
 	if err != nil {

wallet.go

@@ -782,7 +782,7 @@ func (c *Client) AddMultisigAddressAsync(requiredSigs int, addresses []btcutil.A
 
 	addrs := make([]string, 0, len(addresses))
 	for _, addr := range addresses {
-		addrs = append(addrs, addr.EncodeAddress())
+		addrs = append(addrs, addr.String())
 	}
 
 	cmd, err := btcjson.NewAddMultisigAddressCmd(id, requiredSigs, addrs, account)
@@ -832,7 +832,7 @@ func (c *Client) CreateMultisigAsync(requiredSigs int, addresses []btcutil.Addre
 
 	addrs := make([]string, 0, len(addresses))
 	for _, addr := range addresses {
-		addrs = append(addrs, addr.EncodeAddress())
+		addrs = append(addrs, addr.String())
 	}
 
 	cmd, err := btcjson.NewCreateMultisigCmd(id, requiredSigs, addrs)