Protect against empty/invalid log_protect sections

Protect against empty/invalid log_protect sections

Connectivity would fail if the log_protect section of opensrf_core.xml
was empty, or contained only comments, as it does in the default
example. Add a simple guard against this potential problem.  This fix
will also protect against cases where the 'log_protect' section
contains text rather than separate configuration elements.

Credit to Dan Scott for finding the bug and working out how to fix it.

Signed-off-by: Dan Wells <dbw2@calvin.edu>
Signed-off-by: Dan Scott <dan@coffeecode.net>