iOS 8.3 has "hidden" support for the Vulcan salute emoji. You have to copy each one from wherever you can find it (like this Tweet) and create Keyboard shortcuts for them.
Settings app > General > Keyboard > ShortcutsHow do you mean, create a keyboard shortcut?
Settings app > General > Keyboard > Shortcuts
Add New Shortcut...
In the Phrase field, paste one of those emoji's you copied from the tweet link.
In the Shortcut field, type in a word or phrase you want to use to invoke the emoji (e.g., "spock")
Then tap Save
When you are typing in Messages or wherever and you type "spock," you'll see an autocorrect that suggests replacing "spock" with the Vulcan salute emoji.