freeze: include codecs and encodings

These are required for .decode('hex') used in the json module used in
numpy.

Change-Id: Ic7a2ab5cde05789d9e465e875845b296d559783b
pvvtkextensions: import the proper modules

Change-Id: Ic0bed9bb60fc85c2dd3f2b6c20a35b8d0cfe8529