AutoCorrect: Emoji support (en-US)

Modern graphical operating systems have default Unicode 6 support
with several Emojis and other useful special characters. Using
their short names within colons (de facto web standard), now it's
possible to insert them immediately.

For example:

⌨ -> ⌨ (U+2328)
📷 -> 📷 (U+1F4F7)

Change-Id: I189609983281bcfc223cfd39678e92200b826c89