Cleanup directory structure

Stage 1: Cleaning up directory structure.

* src/ - source files for the project
* build/ - scripts and resources related to building the project
* test/ - test scripts
* dist/ - built distribution file(s)
* dist/demo/ - demo solution (moved from test/)

Updated build scripts to point to new paths
Added  build/build_demo.sh script to build dist/demo/

Relates to dropbox#56