Format errors
Ignore artifacts
Cast to string
Build tasks
Support internal Gyazo server
Fix comments
Merge branch 'master' into support-api

Conflicts:
	main.go

Referecnes:
    1.  Golang multipart file upload example - Matt Aimonetti
        http://matt.aimonetti.net/posts/2013/07/01/golang-multipart-file-upload-example/
    2.  Gyazo API
        https://gyazo.com/api/docs/image