Fixes #34 - exportgtfs with non-ascii characters

Also change test3.zip to trigger the bug if reversion
Use raw_id_fields in admin

Fixes #29
Move extra_data from base class to models

Only models that reflect GTFS files need extra data
Removed from Zone, Block, and Shape
It also looks better in the admin this way
On trip, change inbound/outbound to 0/1

GTFS uses to distinguish trips that have the route ID, but go in
different directions.  Outbound/Inbound are suggested interpretations,
not part of the spec.

Fixes #32.
Import GTFS feeds with BOM

The byte-order mark can be used to help some programs detect that a file
is UTF-8 encoded.

Fixes #31
assertEquals -> assertEqual
Clear coverage before measuring converage
Simplify import of stops.txt, BOM support

Pass a filter function to Base.import_txt instead of splitting in
Stop.import_txt.  This has a few benefits:

* Much simplier code
* Base's BOM detection will run on stops.txt (fixes #31)
* Line numbers will be accurate for duplicate detection
check-manifest: Ignore compiled Python files
Documentation for v0.4.1
Merge branch 'release/v0.4.1'