Correct display of project/tenant id on display of credentials

This change corrects the display of ec2 credentails within the
ListEC2Creds method. Added explicit headers and corrected data listt o
specify tenant_id instead of project id.

Change-Id: I2ea579082bee800d774f202bdc38e2d546e57e77
Closes-Bug: #1292337
Merge "Correct display of project/tenant id on display of credentials"