jupiter.sh: Add support for conda channels (#117)
jupiter.sh: Add support for conda channels (#117)

By prepolutating a metadata value at cluster creation, it is
possible to setup additional channels from which to pull packages.
jmbejara/dataproc-initialization-actions,lukeFalsina/dataproc-initialization-actions,pmkc/dataproc-initialization-actions,GoogleCloudDataproc/initialization-actions,dennishuo/dataproc-initialization-actions,lukeFalsina/dataproc-initialization-actions,dennishuo/dataproc-initialization-actions,pmkc/dataproc-initialization-actions,GoogleCloudDataproc/initialization-actions,jmbejara/dataproc-initialization-actions,GoogleCloudDataproc/initialization-actions