Support self-signed certificates from local acme service

[kirca]

Tried to set up a test environment using a local acme server and DNS but client complains because certificates are self signed:

time="2017-11-14T11:37:36Z" level=info msg="process certificate requests for ingresses" context=kubelego 
time="2017-11-14T11:37:36Z" level=info msg="Attempting to create new secret" context=secret name=test6-foo-dev-tls namespace=default 
time="2017-11-14T11:37:36Z" level=info msg="no cert associated with ingress" context="ingress_tls" name=test6-foo-dev namespace=default 
time="2017-11-14T11:37:36Z" level=info msg="requesting certificate for test6.foo.dev" context="ingress_tls" name=test6-foo-dev namespace=default 
time="2017-11-14T11:37:36Z" level=info msg="Attempting to create new secret" context=secret name=kube-lego-account namespace=kube-lego 
time="2017-11-14T11:37:37Z" level=error msg="Error while processing certificate requests: Get https://boulder:4430: x509: certificate signed by unknown authority" context=kubelego 

Any chance to allow this to be enabled with an environment variable?