v0.1.28

• feat(#95): use [email protected].
• fix(#75): use [email protected], which provides extract area fix.
• feat(api): supports extend and embed query params. See HTTP API params docs for more details.
• feat(#94): add placeholder image support in case of error.
• refactor(heroku): remove defaults flags in Procfile (user most specify them via Heroku app init settings).