Powershell script to check windows updates using NRPE/NSClient++

Checks:

• how many critical and optional updates are available
• whether the system is waiting for reboot after installed updates
  Features:
• properly handles NRPE's 1024b limitation in return packet
• hidden updates return OK state
• Performance data in return packet shows titles of available critical updates
• caches updates in file to reduce network traffic, also dramatically increases script execution speed

Return Values for NRPE:

• No updates available - OK (0)
• Hidden Updates only - OK (0)
• Updates already installed, reboot required - WARNING (1)
• Optional updates available - WARNING (1)
• Critial updates available - CRITICAL (2)
• Script errors - UNKNOWN (3)