mgr/dashboard: Improve SummaryService's getCurrentSummary method
Currently this method will return the value of the summary, even if we haven't receive any.
If you call this method expecting to have some data, you code will probably fail or do nothing.
I propose we return an observable, that will only be resolved when we have some data.
Then, in our code, we could subscribe to this and be sure it would always work.
This could be applied to all situation where we are subscribing to the summary and immediately unsubscribe after we get some data.
For example, when determining the releaseName.