Fix buy skill by gold

[hiperesp]

/cf-saveskillstring.asp:

• Input: <flash><intValue>14</intValue><intIndex>3</intIndex><strToken>a</strToken><intCharID>1</intCharID></flash>
• Problem: Only the first byte will be assigned to the string offset in /var/www/html/server-emulator/hiperesp/server/models/CharacterModel.php on line 121

/cf-goldsubtract.asp:

• Input: <flash><intGold>4750</intGold><strToken>a</strToken><intCharID>1</intCharID></flash>
• Problem: This endpoint not exist

How to test:

1: Go to falconreach, then go to left
2: Go to health store and talk to Reens
3: Select Train Alchemy!, then Pay for Training
4: Click in What's the price?, then confirm clicking in Yes
5: See the requests in browser network tab