Fixes: grafana-rpi and grafana armv7 deb packages

[kminehart]

Resolves:

• Storybook is being included in Grafana installers #140
• Issue where the tar.gz was included in the deb installer, doubling its size.
• Issue where we were creating deb packages for rpi that weren't called "grafana-rpi" or "grafana-enterprise-rpi"

Summary after this is implemented:

• We will continue producing a deb package for armhf with the metadata name grafana and grafana-enterprise.
• We will start producing a deb package for armhf with the metadata name grafana-rpi or grafana-enterprise-pri as well.
• We won't be including the entire source grafana.tar.gz in the deb packages :doh:
• We won't be including storybook in those deb packages either.