Refactor/cleanup bootstrap.sh

Summary

* simplify the various functions that call git commands
* pass arguments to functions instead of relying on global variables
* remove trailing white space
* harmonize output messages
* harmonize indentation in the MAIN section
* color codes that work in dash (the ubuntu default shell)

I didn't remove the use of global $ret in  debug(),error(), and success() because i didnt
 think it wouldn't add much value, but i could add that for consistency.

These changes are one step towards making it easy to use a different directory structure
out of the box instead of dropping all the files in $HOME