Create config/database.yml from sample

Otherwise the assets:precompile rake task fails
Remove internal Ruby download link and use public one.
Merge pull request #166 from prometheus/remove-internals

Remove internal Ruby download link and use public one.
Merge pull request #165 from discordianfish/fix-dockerfile

Dockerfile: Create config/database.yml from sample
Add CORS header to embed#show
Allow iframes for all of PromDash.

We want to be able to show any PromDash content in iframes, so this
removes the X-Frame-Options for all views.
Merge pull request #173 from prometheus/allow-iframes

Allow iframes for all of PromDash.
Update README.md
Namespace template vars as var[key]=val in the URL.

This opens up the possibility of using other hashbang query string
variables for purposes other than setting template variables (initial
fullscreen mode, initial time range settings, etc.).
Allow starting a dashboard in fullscreen mode via URL parameters.

https://github.com/prometheus/promdash/issues/127
Merge pull request #174 from prometheus/namespace-user-vars

Namespace user vars and allow starting dashboards in fullscreen mode
Set min/max values on y axes