Wrong variables used in cmd.rb::string_upload

[meowtochondria]

Line https://github.com/delano/rye/blob/master/lib/rye/cmd.rb#L195 should have filepath in place of remote_path, and newcontent in place of str.

[meowtochondria]

https://github.com/delano/rye/blob/master/lib/rye/cmd.rb#L197 needs to have upload replaced with append.