making MarathonHttpError parse response correctly

Fix health check support

Test Plan: Create an app with health checks

Reviewers: merkkila, tberman

Reviewed By: tberman

Subscribers: tberman, justin, stephan, serdar

Differential Revision: http://phabricator.thefactory.com/D2992

Add support for Endpoints retrieved from /v1/endpoints

Summary: Useful for dynamic LB configuration

Test Plan: Point it at a Marathon server and call `.list_endpoints()`

Reviewers: merkkila

Reviewed By: merkkila

Subscribers: tberman, justin, stephan, serdar

Differential Revision: http://phabricator.thefactory.com/D2906

Version bump

Version bump

Use empty lists as default value for list properties

Marathon Client improvements

Summary: Light refactor. More structure, better documentation, and easier app updates and scaling.

Test Plan: Run the examples in README.md

Reviewers: merkkila

Reviewed By: merkkila

Subscribers: tberman, justin, stephan, serdar

Differential Revision: http://phabricator.thefactory.com/D2082

Fix requirements

Bump version