Certain Cart/Checkout translation terms are missing or exist but are not found.

Some terms translations break the file term loading process. If you
move the terms not found to the end, then the translation is found as
expected. Added some missing terms too. I just tested the mo file
included with this commit.
Fix typo in wpsc_minor_option check in wpsc_install()

Fix typo in wpsc_minor_option check in wpsc_install().
Merge pull request #736 from ReactorShop/reactorshop

Sending pull request to sync my repo (minor version typo fix/es_ES po/mo files fix)