Elastic IP isn't associated if one already exists

In order to maintain cross compatibility between openstack and AWS,
an EIP was anyway being attached to the instance.

This patch fixes it.

Signed-off-by: Shashank Sahni <shredder12@gmail.com>
Running multistack-cdh4 cookbook

Using multistack-cdh4 recipe as default now. The CDH4 repo provides
most software in Hadoop ecosystem pre-packaged. Hence, shifting to
it.

Signed-off-by: Shashank Sahni <shredder12@gmail.com>
Auto fetching of Hadoop GID and mapred UID

Instead of keeping hard coded values of hadoop group and mapred user,
this patch adds the feature of fetching the values from the node
itself.

Signed-off-by: Shashank Sahni <shredder12@gmail.com>
Merge pull request #9 from shredder12/master

Shifted to CDH4, no more EIPs and few bug fixes