[compatibility] Refactor while loop for reading directory listing by …

[HuangShumin]

…avoiding to use here-string

here-string is Bash/Ksh/Zsh feature, sh/dash won't support herestring

[stokito]

Thank you for the PR. The dash is not supported by the project, only the BusyBox ash. I'll test it later once finish it.
The project is a playground and it's not completed yet. I just tested that generally the idea works. Even more, in order to work we also need to patch the BusyBox httpd to allow methods other that GET and POST. I'll do this later, now I working on XMPP stuff and will back to WebDAV later.