Address 1.6.1-2.0 upgrade problems reported by Ben Shum

Address 1.6.1-2.0 upgrade problems reported by Ben Shum

1. We were attempting to update the asset.uri ID sequence value
with the wrong syntax; also, adding just 1 would return an error
in the event that only the seed value for asset.uri had been
inserted.

2. Somehow the body of the maintain_control_numbers() function
was pasted twice, resulting in a syntax error.

git-svn-id: svn://svn.open-ils.org/ILS/branches/rel_2_0@18849 dcc99617-32d9-48b4-a31d-7c20da2025e4