Add sitecustomize.py to set Python default encoding to UTF-8

[akaginch]

Since the default encoding of Python 2.x is ASCII, encoding / decoding strings that include non-ASCII characters without explicitly specified encoding causes UnicodeEncodeError / UnicodeDecodeError.

Some useful QGIS plugins (e.g. some algorithms of Processing, and mmqgis) can not be used with non-ASCII data because of this error. We can avoid these errors by simply changing the default encoding to UTF-8. There is no problem related to this change with users who use only ASCII characters. In Python 3.x, the default encoding is UTF-8.

Python code authors still need to pay attention to encoding when writing a code which handles file path or non-UTF-8 data, but have no need to pay attention at any other time.

python27\lib\site-packages\sitecustomize.py:

import sys
sys.setdefaultencoding("utf-8")

[akaginch]

I'm closing this ticket because some modifications can be found in the plugins.