Start-FileSystemWatcher enhancements

[majkinetor]

• Get cummulative list of changes
• Aggregate quick changes to single file (parameter: milliseconds)
• Allow multiple actions (kinda like guard).

[majkinetor]

See https://github.com/smurawski/PowerShellGuard

[majkinetor]

See https://gist.github.com/AnthonyMastrean/4771515