fix uploads of small files
fix uploads of small files

cgi.FieldStorage by default doesn't use make_file.
Only if the file is bigger than 1000 bytes the method is called.
Overriding the private method __write allows to always call the method
independently of file size.

closes #88

scitran/core,scitran/core,scitran/api,scitran/api,scitran/core,scitran/core