Import/export terms with uuid

Hi, Matthias.

Problem/motivation
I faced with a task to migrate a big taxonomy vocabulary (over 4000 terms) from site A to site B and I needed to keep the same term UUIDs. I tried to use uuid_features and it works fine, but if create feature with this big vocabulary it crashes with PDO exception (because features try to add too long string in 'system' table). But your module works fine with big vocabularies import/export, but not works with uuids.

Solution/suggestion
This patch provides possibility to export and import terms with uuid.

How it works:

• Export: if there is installed and enabled uuid module on the site then on taxonomy manager's export form will be checkbox 'Export terms with uuid'. It works with all of export formats (CSV and term names)
• Import: if there is installed and enabled uuid module on the site then on taxonomy manager's import form will be checkbox 'Import terms with uuid'. So you can enter term names with uuid like a "name|uuid"

I hope it useful functionality and will be helpful for other developers and site builders)

Can you review this patch please?