Create street name aliases based on alternate names in TIGER data

[slinkp]

We now use primary names for all blocks/streets loaded from TIGER data, as per issue #278.

It would be great to automatically set up StreetMisspelling? instances based on the alternate names provided by TIGER data, so users could find a street by giving either name. But this is problematic, as discussed at
#4

[slinkp]

Ticket imported from Trac:
http://developer.openblockproject.org/ticket/290
Reported by: slinkp