Support old windows versions

Added a test to not error out when the Appx cmdlets are not available (like in
the windows 7 box i am using). I had some install issues with creating the
bin links so I added "-f".

install/ExtractPrograms.ps1

@@ -329,6 +329,8 @@ Write-Output 'ICONS=()'
 
 # Search for installed applications.
 AppSearchWinReg     # Windows Registry
-AppSearchUWP        # Universal Windows Platform
+if (Get-Command Get-AppxPackage -ErrorAction SilentlyContinue){
+    AppSearchUWP        # Universal Windows Platform
+}
 AppSearchChocolatey # Chocolatey Package Manager
 AppSearchScoop      # Scoop Package Manager