Remove deprecation warning

- remove invalid escape sequence
- use  read_file instead of read_fp
- use importlib instead of imp and __import__
- use callable instead of instance of collections.Callable
- fix silent file closing
- replace SafeConfigParser by ConfigParser
- replace decodestring by decodebytes
- replace encodestring by encodebytes

issue7666
issue7390
review53361004

setup.py

@@ -26,7 +26,7 @@ def get_require_version(name):
 
 
 config = ConfigParser()
-config.readfp(open('tryton.cfg'))
+config.read_file(open('tryton.cfg'))
 info = dict(config.items('tryton'))
 for key in ('depends', 'extras_depend', 'xml'):
     if key in info: