Hooks up yamllint makefile command to "lint" wrapper
Hooks up yamllint makefile command to "lint" wrapper

We're not installing the yamllint package anywhere yet. It should be
available by default in Travis, but I doubt it will be in Circle.

ehartsuyker/securedrop,heartsucker/securedrop,heartsucker/securedrop,ehartsuyker/securedrop,garrettr/securedrop,conorsch/securedrop,micahflee/securedrop,garrettr/securedrop,conorsch/securedrop,heartsucker/securedrop,heartsucker/securedrop,conorsch/securedrop,ehartsuyker/securedrop,garrettr/securedrop,ehartsuyker/securedrop,conorsch/securedrop,ehartsuyker/securedrop,micahflee/securedrop,ehartsuyker/securedrop,heartsucker/securedrop,micahflee/securedrop,conorsch/securedrop,garrettr/securedrop,micahflee/securedrop