Consider a better way to find base path for configuration files

[rynowak]

We found a scenario in our tests where we need to set the base path for loading configuration files. However we have to use AppDomain.CurrentDomain.SetData, as it's not respecting IApplicationEnvironment. It would be nice if we had a non-hack way to do this.

https://github.com/aspnet/Mvc/pull/1056/files#r16626252

https://github.com/aspnet/Configuration/blob/dev/src/Microsoft.Framework.ConfigurationModel/PathResolver.cs#L23

[davidfowl]

You can't set the appbase from within the appdomain. You pretty much need a new process.

[davidfowl]

Looking at the PR comments though I think I know what this is getting at. The real issue is that we're not using the service provider to get the IApplicationEnvironment

[rynowak]

@davidfowl sorry for the confusion, updated the title and comments

[sornaks]

Also, if multiple tests have AppDomain.CurrentDomain.SetData("APPBASE", "basepath");, then the value set by one test gets overwritten by the other. Hence it would be good to remove the dependency on AppDomain.CurrentDomain.BaseDirectory.