Update embedded python3 to latest 3.7

Summary

Update embedded Python from 3.4.8 3.4.9 to latest minor

Proposal

• The included version of Python does not handle bytes/string handling correctly e.g. in the json module while reading from streams.
• Besides a lot of bugfixes are included in newer minors.

References

• https://docs.python.org/3.7/whatsnew/3.7.html
• https://docs.python.org/3.6/whatsnew/3.6.html
• https://docs.python.org/3.5/whatsnew/3.5.html