To install Ansible on most Debian-based distributions, generally the process is extremely simple:

$ # Make sure we have an accurate view of repositories
$ sudo apt-get update

<snip>
Fetched 3,971 kB in 22s (176 kB/s) 
Reading package lists... Done

$ # Install the package
$ sudo apt-get install ansible

Reading package lists... Done
Building dependency tree 
Reading state information... Done
The following NEW packages will be installed:
  ansible
0 upgraded, 1 newly installed, 0 to remove and 30 not upgraded.
<snip>
Setting up ansible (2.0.0.2-2ubuntu1) ...

$ # Sanity check
$ ansible --version

ansible 2.0.0.2
  config file = /home/user/checkout/eos-administration/ansible/ansible.cfg
  configured module search path = /usr/share/ansible