Fix authorized_keys file permissions

Explicitly set the file permissions to be 0600

Fixes LP# 1107908

Change-Id: Ife44deff41959180d31e7e88c29233e9b8cb0af2
Adds API Sample tests for os-instance_usage_audit_log extension.

Fixes Bug 1091752.
Partially implements bp nova-api-samples.

Change-Id: I2db83ac32283795ab0cbf254c6adbd352806b297
Merge "Adds API Sample tests for os-instance_usage_audit_log extension."
Merge "Fix authorized_keys file permissions"