Remove VSCode "post-build" task and .vscode/settings.json

[blake502]

I'm requesting to remove .vscode/settings.json from this repo. From my understanding, Travis no longer uses Visual Studio Code so hopefully this will not cause any annoyance.

I find myself frequently deleting this file, then discarding that change over and over again whenever I work with Kohi in VS Code. Adding this file to .gitignore should allow anybody working with Kohi to use their own settings.json file instead.

If you feel this change is not appropriate for this repo, please let me know!

Additionally-- I've removed the "post-build" task from .vscode/tasks.json since that process was removed in this commit: https://github.com/travisvroman/kohi/commit/b9f1b523a0b737d2a1c6df9d6c648d78044b4008