x509 certificate signed by unknown authority - both with docker and with github

Question

Used the below command for build-

docker build -t oreng/iojs .

INFO[0000] Get https://index.docker.io/v1/repositories/library/iojs/images: x509: certificate signed by unknown authority. 

My DockerFile content is-

FROM iojs:latest
RUN useradd -ms /bin/bash developer
WORKDIR /home/developer
USER developer

Also used the create hub-

Post https://api.github.com/user/repos: x509: certificate signed by unknown authority