add error handling

[jmartin-sul]

e.g. for network timeouts, etc.

a few things i can think of are:

• some sort of error message to both the console and the complete.log output file.
• make sure that an error retrieving an individual resource doesn't cause the whole export attempt to fail
  • but make it clear that there was not full success and that some resources may be missing from the export.

spawned by #1

[justinlittman]

@jmartin-sul suggests that this is closable.

[jmartin-sul]

a little elaboration:

some sort of error message to both the console and the complete.log output file.

console logging (and honeybadger logging) are now both in place. so we should be informed about errors when they occur, including timeouts and the sort of mis-handling described in #49.

make sure that an error retrieving an individual resource doesn't cause the whole export attempt to fail

there is now more robust error handling than when this ticket was filed, and some catch statements have been added that should address this.