Fixes login command issue

Fixes #20
Thanks to @sdahlbac for reporting login command bug

Now Python 3.7+ is required

• Dropped support for deprecated Python version 3.6
• Fixes #18. Thanks @raydouglass for reporting the bug

Now Python 3.6+ is required

• From this release onwards Python 2 support is dropped and now 3.6+ is required for using this package
• This also fixes site-packages/src installation directory issue. Thanks a lot to @sodul for suggesting and sending the fix!

Fix --all-pages bug

Fixes --all-pages bug

--all-pages option added

A new option --all-pages is now supported by tags argument. It will list all pages of the result. Thank you to @tomviner #11

A bug that prevented token from being saved has also been fixed. Thank you to @sdahlbac #13

Config options are here

This release adds support for setting and getting config options.
A fix for login bug has also be added in this release.

Corrects json format

This release corrects json format(when using --format json flag) so that output can be piped into other commands for further processing.

Special thanks to @jessestuart for contributing the fix: #9

Adds support for env based auth

This release adds support for authenticating using DOCKER_HUB_USERNAME, DOCKER_HUB_PASSWORD envs.

Documentation update

nothing much, just readme update

adds login command

This release adds login command with which you can authenticate to docker-hub. If unauthenticated will be querying docker hub without token and will list public resources only.