(GH-439) Refresh Environment Before Package Scripts

Before running each package script, refresh the process environment
variables so that the subprocess will inherit those. This allows
updates to PATH and additional environment variables to be taken
advantage of in packages that may depend on them being set by a package
dependency that installs during the same run.

src/chocolatey/infrastructure.app/services/PowershellService.cs

@@ -192,6 +192,7 @@ public bool run_action(ChocolateyConfiguration configuration, PackageResult pack
                 var failure = false;
 
                 EnvironmentSettings.set_environment_variables(configuration);
+                EnvironmentSettings.update_environment_variables();
 
                 var package = packageResult.Package;
                 Environment.SetEnvironmentVariable("chocolateyPackageName", package.Id);