Make ROOT_DIR more portable

Instead of having a hard-coded User's path, instead use os.path.expanduser and ~ for a more portable path.
Move output print message to respect module import
Refactor line breaks into more natural pattern

Because parenthesis are already used in the lines, and that parenthesis automatically indicate a continuation to the next line, the more harsh back quotes can be removed to use the line's built-in natural breaking points.
Add command line guard

Although the original intent was to use this script also as a command line, this was lost. A call to main() was added (but only to be executed when called as a command line).
Merge pull request #7 from alexKleider/refactor/minor_reorganization

Refactor/minor reorganization