Fix server bug in text protocol string handling.
Fix server bug in text protocol string handling.

- client_handler_free() calls free() on OML string values, but
  the text protocol handler wasn't malloc'ing them -- it was
  only copying pointers into the receive buffer.
- changed text protocol handler to always malloc/realloc space
  for string values.
- Fixes #266.

alco90/soml,mytestbed/oml,mytestbed/oml,lees0414/EUproject,alco90/soml,alco90/soml,lees0414/EUproject,alco90/soml,lees0414/EUproject,lees0414/EUproject,mytestbed/oml,lees0414/EUproject,alco90/soml,mytestbed/oml,mytestbed/oml