Update cjdns.sh

1. CJDPATH is declared _with_ the trailing slash, but in function update() it is assumed to have no slash at the end. Corrected this. No trailing slashes in path variables now.
2. In echo output, cjdns is spelt inconsistently -- uppercase in some places and lowercase in others. Corrected this. Uppercase everywhere now.
3. Misc typos, like "ot" instead of "to". Corrected.