Combine 'Download' and 'Expand' solr tasks using unarchive

[geerlingguy]

Since 2.0 is pretty much everywhere, we can use unarchives ability to download and expand-into-place the Solr archive.

Currently, the download file sits on the system after the role is finished, but that's annoying... it's like 150MB! And it's causing downstream projects to also be larger than necessary. See, for example: https://github.com/geerlingguy/docker-image-solr/issues/5

Basically, with Ansible 2.x, we should be able to combine these two tasks:

- name: Download Solr.
  get_url:
    url: "{{ solr_mirror }}/lucene/solr/{{ solr_version }}/{{ solr_filename }}.tgz"
    dest: "{{ solr_workspace }}/{{ solr_filename }}.tgz"
    force: no

- name: Expand Solr.
  unarchive:
    src: "{{ solr_workspace }}/{{ solr_filename }}.tgz"
    dest: "{{ solr_workspace }}"
    creates: "{{ solr_workspace }}/{{ solr_filename }}/CHANGES.txt"
    copy: no

Also, related: #14

[geerlingguy]

...of course I forgot that the Solr download script is looking for the source repo :/