This is a really simple plug-in that export all the images in all you materials out at once. 
Just goto File/Export/Export Texture Images to Folder

a window will pop open just choose the folder you want all the texture images to goto.

They will all at once save them to that folder.

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To install goto Edit/Preferences 
Add-ons tab
Install from disk

Then select the zip file --- TextureImageExport.zip

and you are good to go. :)