Importer Re-factor Complete

[Greg Taylor]

Since we've now got more than two people contributing to the project,
it spurred me to finish the re-factoring of the importers. Those of
you who have been poking at them in the last few months will not see
anything majorly new or alarming in the importer classes.

Big differences:
* The importers now show a progress bar along with an ETA. And there
was much rejoicing.
* run_importer() no longer exists on the importer classes. It has been
replaced with import_row(self, row), which imports a single row.
* Each importer class no longer contains its own SQL query and other
repetitive stuff. The table name is determined based on the importer's
class name. The previous requirement that the importer name match the
table name is now an unavoidable thing (which is good for
consistency).

I think I've got these importers distilled down to bare bones, but I'd
love to have some other people help by resetting their eve_db app and
running the importer all the way through.

Let me know if there are any questions.