Added overload to Raven Health check to allow user to pass RavenDBOptions

[ankitvijay]

With this pull request, I have added a method overload to allow user to pass array of Raven URLs RavenDBOptions instead of just single connection string. Note that existing method which allows the user to pass single connection string is still there but it has been marked Obsolete.

Why this change?

• This change is useful to test the health check for the Raven DB Cluster (that is multiple nodes) instead of a single connection string. For Load Balance and Fail over scenarios we would have multiple connection strings instead of one.
• In addition to this, RavenDBOptions also supports certificate authentication. That is user can optionally pass the authentication certificate, which should ideally be a requirement for any production workload (like ours)

As an alternate (without the changes in this PR), we can add multiple raven DB urls as pseudocode below:

    var counter = 1;
    foreach(var url in urls)
    {
        healthCheckBuilder.AddRavenDB(url, "DemoDbName",$"ravendb node{counter}, url: {url} ");
        ++counter;
    }

However, this is less than ideal for following reasons:

• It means additional lines of code.
• If one of urls is down/ unavailable the overall health status would be returned as "Unhealthy" which is incorrect since server can still connect to the alternate Raven DB url.
• In scenarios where authentication is required we cannot use this health check library.

[unaizorrilla]

Hi @ankitvijay

I try to review this ASAP!

[unaizorrilla]

Hi,
@ankitvijay sounds good. I summitted some minor changes, can you address this?

[ankitvijay]

Hi @unaizorrilla when you get a chance could you look into my PR please. I'm waiting for it to merge to start using it my project. Thanks!

[unaizorrilla]

Yeap, tomorrow!

[unaizorrilla]

Merged, thanks for contributing. Build Release is on appveyor, when finish a new package 2.2.2. for RavenDb will be on NuGet.

[ankitvijay]

Thanks @unaizorrilla