Changed "Task Details" to "Task Execution Details"
Changed "Task Details" to "Task Execution Details"

The task execution details view was incorrectly titled as "Task
Details". This patch changes it to "Task Execution Details".

Change-Id: I53504461177594c837d4433ae9b4469729a8753e
Closes-Bug: #1648432

openstack/mistral-dashboard,openstack/mistral-dashboard,openstack/mistral-dashboard