Update sqlalchemy

Based on https://github.com/geoadmin/mf-chsdi3/pull/1143 (To be merged first)

This PR updates psycopg2, SQLAlchemy, GeoAlchemy and Papyrus to their latest versions.

With the update of postgresql and postigis (2+), I thought updating those librairies made sense.

We moved forward to geolachemy2 and I am using a work Eric has recently made to update papyrus accordingly.
https://github.com/elemoine/papyrus/commit/b630639f9b9e69f2bfeb9c18b8e5f64039d3b395
https://github.com/elemoine/papyrus/issues/23

For SQLAlchemy, here are the changes:
http://docs.sqlalchemy.org/en/rel_0_8/changelog/migration_08.html
http://docs.sqlalchemy.org/en/rel_0_9/changelog/migration_09.html

And GeoAlchemy
http://geoalchemy-2.readthedocs.org/en/latest/migrate.html#migrate

I tested everything and it seems pretty solid.