_devel_backend.sh: fix `node` path to allow system's "$PATH" under GNU/Linux
_devel_backend.sh: fix `node` path to allow system's "$PATH" under GNU/Linux

NOTE: runs from where it is
Under Linux `node`	executable can be in `/usr/bin` or `/usr/local/bin`.
Under MS Windows it is better to have `node.exe` (and all cygwin stuff)
nearby.

olecom/enjsms,olecom/enjsms