Swiftbits Icon

Working on an update for http://kaishin.github.io/learn-swift/ with Swift 2.0 syntax and new tutorials/resources.

I decided to rename the website to Swiftbits to make it more identifiable and search-engine friendly.

The icon uses the same color palette as the current version and is based on a hybrid between the Swift logo and the Japanese symbol for "beginner" (🔰).