Don't consume bonemeal if there is no crop in front. Fixes BUKKIT-3790


#### The Issue

A dispenser stocked with bonemeal will fertilize a crop in front of it. However, if a crop is not present the dispenser will still consume bonemeal. 

#### Justification for PR

The behaviour of the vanilla server is different, as it will not consume bonemeal if there is no crop. This behaviour also seems to make more sense.

#### PR Breakdown

If ```ItemDye.a(itemstack1, world, i, j, k)``` returns false, indicating a crop was not present, the item stack count will be incremented by one to produce the original value.

#### JIRA Ticket

BUKKIT-3790 - https://bukkit.atlassian.net/browse/BUKKIT-3790