sautils 0.4

Various SQLAlchemy utilities which are a little specific to be proposed to
main SQLAlchemy distribution.

Currently the following features are supported:

- insert_from_select(table, select) -- adapted from corresponding SQLAlchemy
example (all copyrights goes to @zzzeek)

- upsert_from_select(table, select) -- upsert via insert from select with left
join on target table

- upsert(table, **values) -- upsert of values

- sqltype(name) -- shortcut for defining ad-hoc types