As per #60 - a OCIOCDLTransform Nuke node, along with a bunch of buttons to import/export .cc/.ccc files

Not entirely sure about the node name, but OCIOCDLTransform seemed more consistent with CDLTransform in the config

There are buttons in the node to import and export a .cc file. Also a new Color > OCIO > Utils menu, to create a node for each ColorCorrection in a .ccc, and to export a bunch of nodes as a .ccc

If you import a .ccc file in the node, it'll display a "select a cccid" dialog - was planning to use the same dialog for the OCIOFileTransform, when a .ccc file is loaded