New version with PGID < 1000 support

- support now PGID < 1000 e.g. 100 which is typical for users

- created CHANGELOG.md and updated README.md
- base image is now technosoft2000/alpine-base:3.6-2

New version based on Alpine 3.6

- fixed an issue with kindlegen

- added additional dependencies and an environment variable
- updated README.md and CHANGELOG.md

Small updates

v1.1.1

- updated Dockerfile with version number v1.1.1

Google Drive integration

v1.1.0

- updated README.md regarding latest changes

First release

v1.0.0

- calibre-web image is based now on ```technosoft2000/alpine-base:3.5…