Not sure who thought it was a good idea to make this happen. Its absolutely terrible for Map Makers, especially when you need players not to jump. Jump Boost 128+ makes players not jump, but if you want them to PvP as well, forget it. Jump Boost shoots them in the air if you hit the player with Jump Boost twice. Ridiculous... :L
I used this:
/give @p skull 1 3 {SkullOwner:{Id:"30c793d3-5755-455d-94bb-6b71c18be47c",Properties:{textures:[{Value:"eyJ0aW1lc3RhbXAiOjE1MDU4NTgzNjE2ODQsInByb2ZpbGVJZCI6IjMwYzc5M2QzNTc1NTQ1NWQ5NGJiNmI3MWMxOGJlNDdjIiwicHJvZmlsZU5hbWUiOiJfRGVzc2llIiwidGV4dHVyZXMiOnsiU0tJTiI6eyJ1cmwiOiJodHRwOi8vdGV4dHVyZXMubWluZWNyYWZ0Lm5ldC90ZXh0dXJlLzhmNzlhMDM5OTk2OWNiOTFmMzVmMWNhNmQ1ZTMyZDkzMmRmM2VmZWUyNmNjMTg2YWE5OWI3ZjdiMzdiMjU1OSJ9fX0="}]}}}
I had two of these going (With different texture values) and they gave the same thing. They both give alex skins now.