[PATCH] Add the ability to specify in the configuration file the cost and the required level for training and acquiring both normal and epic mounts.

Hi, as discussed in issue https://github.com/mangoszero/server/pull/167 (@billy1arm) the following is the requested patch for mangos-one. The default mount prices (without faction reduction) have been extracted from the database and I will post them here for reference:

| Setting  | Default Value |
| ------------- | ------------- |
|  MountCost  | 100000 (10g)  |
| TrainMountCost  | 350000 (35g)  |
| MinTrainMountLevel | 30 (level 30) |
| EpicMountCost | 1000000 (100g) |
| TrainEpicMountCost | 6000000 (600g) |
| MinTrainEpicMountLevel | 60 (level 60) |

As you can observe, the difference from mangos-zero is that Blizzard lowered the level requirement to level 30 from level 40, made the price of the normal mount 35g instead of 90g as well as lowering the price for the epic mount to 600g instead of 900g.

This patch addresses ground mounts only. A future patch may address the prices and the requirement levels of flying mounts (although this will have to be done hand-in hand with a patch concerning the flying abilities due to the fact that in a vanilla Blizzard-like configuration, flying is allowed only in certain areas).