PowerShell Error: Add-Type: Could not load file or assembly 'file:///C:\Program Files\Common Files\Micros oft Shared\Web Server Extensions\15\ISAPI\Microsoft.SharePoint.Client.dll' or one of its dependencies. This assembly is built by a runtime newer than the currently loaded runtime and cannot be loaded

Problem: 
When trying to write a client side PowerShell script for SharePoint online, got an error:

Error: Add-Type : Could not load file or assembly 'file:///C:\Program Files\Common Files\Micros
oft Shared\Web Server Extensions\15\ISAPI\Microsoft.SharePoint.Client.dll' or one of its  dependencies. This assembly is built by a runtime newer than the currently loaded runtime and cannot be loaded.
Verified SharePoint Server 2013 Client Components SDK is already installed to use Client side assemblies. (if not,  You can download it from: http://www.microsoft.com/en-us/download/details.aspx?id=35585)

Solution:
You need to have PowerShell 3.0 to use Client side assemblies of SharePoint online. So, download and install "Windows Management Framework 3.0" at https://www.microsoft.com/en-us/download/details.aspx?id=34595