(GH-818) Wait for processes to exit + 2 seconds

There are cases when the process has signalled it has exited, but it
hasn't actually returned an exit code yet. Hold for 2 seconds to allow
the process to fully exit before attempting to capture the exit code.

src/chocolatey.resources/helpers/functions/Get-ChocolateyUnzip.ps1

@@ -166,6 +166,9 @@ param(
   Unregister-Event -SourceIdentifier "LogOutput_ChocolateyZipProc"
   Unregister-Event -SourceIdentifier "LogErrors_ChocolateyZipProc"
 
+  # sometimes the process hasn't fully exited yet.
+  Start-Sleep 2
+
   $exitCode = $process.ExitCode
   Set-PowerShellExitCode $exitCode
   $process.Dispose()

src/chocolatey.resources/helpers/functions/Start-ChocolateyProcessAsAdmin.ps1

@@ -156,7 +156,7 @@ Elevating Permissions and running [`"$exeToRun`" $wrappedStatements]. This may t
 
   $process = New-Object System.Diagnostics.Process
   $process.EnableRaisingEvents = $true
-  Register-ObjectEvent  -InputObject $process -SourceIdentifier "LogOutput_ChocolateyProc" -EventName OutputDataReceived -Action $writeOutput | Out-Null
+  Register-ObjectEvent -InputObject $process -SourceIdentifier "LogOutput_ChocolateyProc" -EventName OutputDataReceived -Action $writeOutput | Out-Null
   Register-ObjectEvent -InputObject $process -SourceIdentifier "LogErrors_ChocolateyProc" -EventName ErrorDataReceived -Action  $writeError | Out-Null
 
   #$process.StartInfo = New-Object System.Diagnostics.ProcessStartInfo($exeToRun, $wrappedStatements)
@@ -191,6 +191,9 @@ Elevating Permissions and running [`"$exeToRun`" $wrappedStatements]. This may t
   # them to do so. Without this it never finishes.
   Unregister-Event -SourceIdentifier "LogOutput_ChocolateyProc"
   Unregister-Event -SourceIdentifier "LogErrors_ChocolateyProc"
+
+  # sometimes the process hasn't fully exited yet.
+  Start-Sleep 2
 
   $exitCode = $process.ExitCode
   $process.Dispose()