Acumen 2016.08.30

modify various information files

Changes included in this commit:
- Added gui's demo image in src/main/resources/acumen/ui/tl/images
  for use in README.md
- Removed release notes from README.md and moved them
  to a new file RELEASE-NOTES.md
- Renamed README-developers file to CONTRIBUTING.md
- Fixed various typos in CONTRIBUTING.md and .gitignore
- Modified mk_jar.sh file to use assembly to build package