[IMPROV] Use 'io' package also in Python 2.6

This also fixes a problem with flickrripper in Python 3, because it
stored the binary image data into a StringIO and not BytesIO object.

Change-Id: I79703aa4d3a3d1df5cea546cb18152305c3b0cd4
Merge "[IMPROV] Use 'io' package also in Python 2.6"