Check $Help parameter explictly

This is just to squash PSSA telling us that
the -Help parameter is defined but not used.

Author: devblackops

build.ps1

@@ -25,10 +25,10 @@ if ($Bootstrap.IsPresent) {
 # Execute psake task(s)
 $psakeFile = './psakeFile.ps1'
 Set-BuildEnvironment -Force -WarningAction SilentlyContinue
-if ($PSCmdlet.ParameterSetName -eq 'Help') {
+if ($Help.IsPresent) {
     Get-PSakeScriptTasks -buildFile $psakeFile  |
         Format-Table -Property Name, Description, Alias, DependsOn
 } else {
     Invoke-psake -buildFile $psakeFile -taskList $Task -nologo -Verbose:($VerbosePreference -eq 'Continue')
     exit ([int](-not $psake.build_success))
-}
+}