private_api: fix setup-checkout call

The options hash for active merchant expects symbols for keys
but we were passing a version with string keys instead (from the JSON
body).

Thank you Rails again for letting me not write code.

Signed-off-by: Pierre-Alexandre Meyer <pierre@ning.com>
version: bump to 1.0.10

Signed-off-by: Pierre-Alexandre Meyer <pierre@ning.com>