Include `dstat.rb`.

This commit refs #74.
Install the prerequisite gems for collecting `dstat` data.

This commit refs #74.
Deploy the configuration file for processing dstat data on the manager's server.

This commit refs #74.
Deploy the configuration file for collecting and forwarding `dstat` data.

This commit refs #74.
Modify the conditional to follow the foodcritic's advice.

This commit refs #74.
Merge pull request #74 from kazu634/id/74

[GrowthForecast] dstatの結果をグラフ化する