Support custom zookeeper debian apt repository (to use v3.4.8 on Ubuntu 14.04

[lhoss]

by allowing to configure a custom (ppa) apt repos, we can use a community provided v3.4.8 deb-pkg based deployment (which is more secure than using 'tarball' , when later installing mesos which by default has 'zookeeper' in its dependencies).

Example config to make this work:

      zookeeper_debian_apt_repository: "ppa:ufscar/zookeeper"
      zookeeper_debian_apt_install: true
      zookeeper_version: 3.4.8

[ernestas-poskus]

@lhoss please update README as well and you can include your example

[lhoss]

@ernestas-poskus done including a more flexible way to define different repositories for different distribution versions (resp. this properly limits to add the repository only for the supported distro, as for ex. to deploy v3.4.8 on Ubuntu 16.04 does not require any additional repo)

[lhoss]

ps: I also bumped (long time outdated) zookeeper_playbook_version , but I guess both following vars you can simply remove from the defaults ( and the README)

ansible_playbook_version: 0.1
zookeeper_playbook_version: "0.17.0"

[ernestas-poskus]

Will remove this zookeeper_playbook_version var

[ernestas-poskus]

Thank you for contribution 👍