[B] Update API for Acacia & Dark Oak. Fixes BUKKIT-4988

##### The Issue:

When Minecraft 1.7 was released, Acacia and Dark Oak TreeSpecies were
added. While Bukkit added them to TreeSpecies it did not add support in
getSpecies() and setSpecies().

Currently Acacia (0x4) is reported as Oak (0x0) and Dark Oak (0x5) is
reported as Spruce (0x1). 


##### Justification for this PR:

This fixes a bug the usage of the new tree types.


##### PR Breakdown:

This pull requests changes the bit field protection from 0x3 to 0x7 and from 0xC to 0x8. This way the new values of 0x4 (Acacia) and 0x5 (Dark Oak) are properly supported.


##### JIRA Ticket:

BUKKIT-4988 - https://bukkit.atlassian.net/browse/BUKKIT-4988