tests: Test table migration in repository test
tests: Also test closing the database
gom: Roughly document gom_adapter_open_async()

URL in the text should probably be an hyper-link, but that will do
for now.
gom: Actually open URIs passed to open() as URIs

And not filenames by setting the SQLITE_OPEN_URI open flag as
mentioned in:
http://www.sqlite.org/uri.html