Set tenant headers from ec2 authentication.

Without this, ec2token middleware on its own doesn't set enough
headers to perform heat requests.

Change-Id: I7a0867196741c0df222d491fb1bfbe203158032c
Set role headers from ec2 authentication.

Without this roles are not available in the context when
ec2token middleware is used on its own.

Change-Id: I1214e44c588f547ee6f90f0f71a085f786e7ea7f
Merge "Set tenant headers from ec2 authentication."
Merge "Set role headers from ec2 authentication."