How can you remove all of the trailing whitespace of an entire project? Starting at a root directory, and removing the trailing whitespace from all files in all folders.
Instead of excluding files, here is a variation of the above the explicitly white lists the files, based on file extension, that you want to strip, feel free to season to taste:
find . \( -name *.rb -or -name *.html -or -name *.js -or -name *.coffee -or \
-name *.css -or -name *.scss -or -name *.erb -or -name *.yml -or -name *.ru \) \
-print0 | xargs -0 sed -i '' -E "s/[[:space:]]*$//"