SQLite provider doesn't create indexes on foreign key columns

[bojanrajkovic]

The SQLite provider claims it creates indexes on foreign key columns (http://ef.readthedocs.org/en/latest/modeling/indexes.html#conventions), but it actually doesn't in practice.

[bricelam]

Dupe of #700?

[bojanrajkovic]

Seems like it, though this is specific to the SQLite provider. Not sure if the other providers do this correctly.