BUG26847553: Fix AttributeError when using pure Python Protobuf

Using a value of type list when setting an attribute in a Message object
throws an AttributeError.

This patch fix this issue by testing the value type and using the .extend()
method for list type values.

This patch also adds the encoding of string values types to bytes when using
Python 3.

Update CPYINT revision

Update CPYINT revision

Add Python 3.4 and 3.5 as supported versions

Update CPYINT revision

BUG25215081: Remove dictionary comprehension lists

Dictionary comprehension lists is not supported in python 2.6 which causes
this error. Using the dict initializer with tuple works the same as
dictionary comprehension lists and is also supported in python 2.6.

Update CPYINT revision

Fix copyright year in README.txt

Fix TypeError exception found in BUG22529828 patch using Python 2

Removed BUG23722871 fix changelog entry as requested by QA