Automatic migration of CCK fields and imagecache presets

Hi there, I've re-inserted the automatic migration of CCK content fields and also added the upgrade of all imagecache presets. I'm attaching the patch against the 7.x-2.x-dev branch.

In addition, I've provided other minor improvements:

• if mode is auto, skips backup after each contrib module, as each archive-dump was taking too much time
• provided an additional backup checkpoint after content-migrate-fields has run (before the contrib modules are upgraded)
• provided an additional backup checkpoint after _all_ the contrib modules and the imagecache presets have been upgraded
• added a mapping of i18n project, which changed their module names

It's been fun working with the module's code. I hope you find these additions relevant enough to be commited. Please let me know if you have any questions.