Change Log for PSScriptTools

v2.15.0

• Added Get-FolderSizeInfo and its alias gsi along with a corresponding format.ps1xml file.
• Fixed IsWindows bug in New-WPFMessageBox (Issue #59)
• Fixed IsWindows bug in Convertto-WPFGrid, Find-CimClass, Test-ExpressionForm, Get-WindowsVersion,Get-WindowsVersionString and Invoke-InputBox by using a new function Test-IsPSWindows
• Updated Get-PSWho to better work cross-platform
• Help updates
• Updated README.md