Making author summary queries less brittle

The $unwind Mongo function is really picky about the data, and there
are a few instances where the authors field has bad data. This change
should filter out that bad data before passing on to $unwind.
Use lineno instead of filelineno for input script
Simplify logging interface

All the request logging is now handled by a single logger with multiple
handlers. The RequestFilter class controls which messages are logged by
examining the err_type property of the log record.
Specify settings as filename rather than module

The previous settings import was a bit wonky and limited. The app
config setting is now expected to be a filename, rather than a string
representing an importable module name.
Move settings template out of pipeline
Refactor pipeline steps into importable module
Remove custom log formatter
Change default settings location for summary
Add global exception handler
Add filter for crawlers
Merge pull request #10 from gravesm/master

More pipeline tweaks