Rename github_token config to gcg_github_token
Rename github_token config to gcg_github_token

Since it is likely we will need multiple tokens for different programs
with different permissions, make the token configuration specific to the
application which requires.

Signed-off-by: Kevin Locke <ffb4761cba839470133bee36aeb139f58d7dbaa9@kevinlocke.name>

kevinoid/node-project-template,kevinoid/swagger-spec-validator,kevinoid/swagger-spec-validator,kevinoid/appveyor-status,kevinoid/travis-status,kevinoid/stream-compare,kevinoid/node-project-template,kevinoid/appveyor-status,kevinoid/git-branch-is,kevinoid/promised-read,kevinoid/appveyor-status,kevinoid/travis-status,kevinoid/promised-read,kevinoid/stream-compare,kevinoid/travis-status,kevinoid/swagger-spec-validator,kevinoid/git-branch-is,kevinoid/stream-compare,kevinoid/git-branch-is,kevinoid/node-project-template,kevinoid/promised-read