Store hash of access as primary key for ec2 type.

In current v3 credential implementation when
a new ec2 credential is created we store it with
new credential id in the backend. This fix is provided
to store the hash of access key id as credential
id when a new ec2 v3 credential is created.

Fixes Bug #1185582

Change-Id: I0ad9aaa3282b101adb6228582f0d24349232ce18
Merge "Store hash of access as primary key for ec2 type."