Make InvalidInstanceIDMalformed an EC2 exception

Rename InvalidInstanceIDMalformed to InvalidInstanceIDMalformedEC2
and add ec2_code attribute to make it proper EC2 API exception.

Implements: blueprint ec2-error-codes
Change-Id: I8841f79890e087b850801bf71da0512bd329d5df
Merge "Make InvalidInstanceIDMalformed an EC2 exception"