Build with docker

[ThorstenBux]

This PR add the Docker support for the build system. Based on the discussion in the PR #1 and issues #11 #10 #12
Docker is the recommended tool for building the libs.

• added informations for building with Docker in the README.md file
• added -s USE_LIBJPEG flag to the makem.js: by emscripten v1.38.31 you can include libjpeg in the project without adding any libs or headers files.
• removed the libjpeg.bc file and other part of libjpeg references in the makem.js node script.
• updating istructions in disencuraged-build-local-with-manual-emscripten-setup section of the README.md
• removed build.sh script
• re-added the flag ' -s BINARYEN_TRAP_MODE=clamp' for nft + wasm compilation
• other fixex in conf.json and package.json

[kalwalt]

@ThorstenBux In the README.md should be updated also the section disencuraged-build-local-with-manual-emscripten-setup
the 9 point should be:

+npm run build-local
-npm run build

and we can delete also the points 3 and 4 about libjpeg.

[kalwalt]

i tested also your latest changes fa89ed2 , as
i suggested in #12, with Docker and works perfectly!

[ThorstenBux]

Updated and pushed. You may have a look at it again and merge if you think it is good.

[kalwalt]

I think it is ok. We can go over, for other improves in the code. Thank you!