Correctly handle spaces in file paths

[wdn]

Since install_dotfiles() in bootstrap treats the output of find as a list rather than an array, paths with spaces in them will break. The simplest solution is to change the Internal Field Separator to a newline, as it is extremely unlikely that any filenames will contain that character.

Alternatively, the result of find could be put into an array, as demonstrated by this answer, but this seems like a reasonable fix for the vast majority of cases.