profile_tasks README.md

As agreed with Brian Coca in Ansible Project group:
https://groups.google.com/forum/#!searchin/ansible-project/tom$20paine/ansible-project/__nv6BZs2yU/AkYQ0HU-BQAJ

lib/ansible/plugins/callback/profile_tasks.md

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+# profile_tasks.py
+Ansible plugin for timing individual tasks and overall execution time.
+
+Mashup of 2 excellent original works:
+- (https://github.com/jlafon/ansible-profile)
+- (https://github.com/junaid18183/ansible_home/blob/master/ansible_plugins/callback_plugins/timestamp.py.old)
+
+## Usage
+
+Add `profile_taks` to the `callback_whitelist` in `ansible.cfg`.
+
+Run playbooks as normal.
+
+## Features
+
+### Tasks
+
+Ongoing timing of each task as it happens.
+
+Format:
+`<task start timestamp> (<length of previous task>) <current elapsed playbook execution time>`
+
+```shell
+TASK: [ensure messaging security group exists] ********************************
+Thursday 11 June 2017  22:50:53 +0100 (0:00:00.721)       0:00:05.322 *********
+ok: [localhost]
+
+TASK: [ensure db security group exists] ***************************************
+Thursday 11 June 2017  22:50:54 +0100 (0:00:00.558)       0:00:05.880 *********
+changed: [localhost]
+```
+
+### Play Recap
+
+Recap includes ending timestamp, total playbook execution time and a sorted list of the top longest running tasks.  
+
+No more wondering how old the results in a terminal window are.
+
+```shell
+   ansible <args here>
+   <normal output here>
+   PLAY RECAP ******************************************************************** 
+   Thursday 11 June 2016  22:51:00 +0100 (0:00:01.011)       0:00:43.247 *********
+   ===============================================================================
+   really slow task  | Download project packages----------------------------11.61s
+   security | Really slow security policies----------------------------------7.03s
+   common-base | Install core system dependencies----------------------------3.62s
+   common | Install pip------------------------------------------------------3.60s
+   common | Install boto-----------------------------------------------------3.57s
+   nginx | Install nginx-----------------------------------------------------3.41s
+   serf | Install system dependencies----------------------------------------3.38s
+   duo_security | Install Duo Unix SSH Integration---------------------------3.37s
+   loggly | Install TLS version----------------------------------------------3.36s
+```
+
+## Compatibility
+
+Ansible 2.0+