* Consistent license message for all the go files
* Fixing the last set of unconsistencies with the license headers
* Addressing PR review comments
* Fixing busy.go and busy_test.go license header
* Emoji validation fails if name exists in system emojis
* Use hashmap instead of array to improve performance
* Changed utils/StringInMap to emoji/isSystemEmoji
* Load system emojis from model/emoji.json
* Added emoji.json from webapp
* Load system emojis from emoji_data.go instead of emoji.json
* Run `gofmt -w model/emoji_data.go`