Upper-case hostname annotations cause breakage with Route53

[gtie]

We had a case where Services annotated with upper-case hostnames (.e.g 5HW598OVOMBY.foo.bar.com) block further updates. What happens is that ExternalDNS is still trying to create the record, but fails due to a lower-case version already existing:

time="2018-05-16T11:53:48Z" level=error msg="InvalidChangeBatch: Tried to create resource record set [name='5hw598ovomby.foo.bar.com.', type='A'] but it already exists status code: 400, request id: cb487bc6-58ff-11e8-b17c-a32c02ab9e06"

The combination with the batchUpdate problem (#421) makes this issue particularly nasty, potentially disabling updates for everybody because of a single use of upper-case.

[njuettner]

Fixed in 0.5.4 https://github.com/kubernetes-incubator/external-dns/releases/tag/v0.5.4