Grid plugin: docker management

[elgalu]

Use the grid plugin to:

• create a new container when a new selenium session is created
• destroy the container the the selenium session is deleted

Ref:
https://github.com/docker-java/docker-java

[elgalu]

@diemol is working on this, updates will be posted here later on

[diemol]

Zalenium is already open source with its first release, you can try it out.
https://github.com/zalando-incubator/zalenium

[elgalu]

Works!!!!!