Errors reported by the FPA should be addressed

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When the FPA starts up, a bunch of this is typically seen:

ESC[1;31m2018-05-03 20:20:03 [ERROR] _receiver_fpa.cc(246): Exiting due to stream errorESC[0m
ESC[1;31m2018-05-03 21:13:01 [ERROR] _receiver_fpa.cc(246): Exiting due to stream errorESC[0m
ESC[1;31m2018-05-03 22:11:23 [ERROR] _receiver_fpa.cc(246): Exiting due to stream errorESC[0m
ESC[1;31m2018-05-03 22:11:30 [ERROR] _receiver_fpa.cc(246): Exiting due to stream errorESC[0m
ESC[1;31m2018-05-03 22:18:23 [ERROR] _receiver_fpa.cc(246): Exiting due to stream errorESC[0m

And then the errors stop and Psyllid goes on its way in an apparently normal state.

Here's the relevant piece of code from packet_receiver_fpa.cc, starting at line 244:

                        if( ! out_stream< 0 >().set( stream::s_run ) )
                        {
                            LERROR( plog, "Exiting due to stream error" );
                            break;
                        }

There are two problems here:

1. Since Psyllid is in an apparently normal state after those messages, that indicates that there really isn't an error. Whatever the issue that prevents the FPA from writing to its output stream when it starts up, that should be handled without spitting out a bunch of error messages.
2. When there is an error message at this point in the code, the FPA should actually exit instead of breaking out of an inner loop and then continuing to run. Unless that is in fact the desired behavior, in which case this should be a warning message.

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This will be addressed by #78.