Add git

git is not required by bitbucket.pex but if we use it, we probably need
git on the machine.
It ensures git is installed on jenkins slaves.

tasks/main.yml

 ---
+- name: install git
+  yum:
+    name: git
+    state: present
+
 - name: download bitbucket.pex
   get_url:
     url: "{{ bitbucket_pex_url }}"