Use stops instead of shapes to determine SRID

[kshepard]

The file: shapes.txt is optional, so it can't be used to determine the SRID. Instead, use stops, which have a geometry and are required.

[ddohler]

+1; were you able to calculate indicators against systems that are missing trip shapes (excluding the ones that rely on the shapes)?

[kshepard]

Yes, the indicators that rely on shapes all return 0's, and the remaining indicators calculate fine. The map is much less interesting, because the shapes are what are used to display the indicator results.