Update session data for seed cities

[walter]

Now that the year has turned over from 2013 to 2014, some of the seed cities may have had their current session change.

See https://github.com/opengovernment/askthem/blob/master/app/models/metadatum/seed_cities.rb#L34-L38.

[walter]

Double checked the data.

• Chicago and San José have their current term end 2014 (two years, 2013 and 2014).
• Philadelphia is a four year term which started 2012 and ends 2016.

Nothing needs updating this year.