Upgrade bundled Jedi

[segevfiner]

Environment data

VS Code version: 1.19.3
Python Extension version: 0.9.1
Python Version: 2.7.12
OS and version: Ubuntu 16.04.3 x64

Jedi 1.11.1 is available. Might want to consider upgrading, assuming that the new version is better...

Note that it now depends on parso which will also need to be included.

[DonJayamanne]

We've looked the a previous version of Jedi, however there were a number of breaking changes.
This was looked at as part of #171

TODO: Guess its time to review this once again.

[gandhis1]

+1 on this one, I know there's been a large number of fixes and improvements in recent versions. I've also had trouble in the past using anything but the bundled version of Jedi, not sure if these issues have been addressed lately or not.

[balta2ar]

It looks like another version might be ready for a release soon (davidhalter/jedi#1031 (comment)) so maybe it's worth waiting a little more for it (though there is a risk to get stuck in such waiting for a while).