Fix Multiverse/Multiverse-NetherPortals#68

This was caused by Bukkit/CraftBukkit@de86f8c
Merge pull request #70 from Peter200lx/ISSUE-68

Fix Multiverse/Multiverse-NetherPortals#68
Merge branch 'master' of https://github.com/Multiverse/Multiverse-NetherPortals
Don't handle portals which are handled by Multiverse-Portals.
Merge pull request #73 from cybertiger/master

Don't handle portals which are handled by Multiverse-Portals.
Merge branch 'master' of https://github.com/Multiverse/Multiverse-NetherPortals