Fixed 2 sv vocab bugs for 3-1 hotfix.  #1454

Fixed two bugs.

1. When a vocab wasn't selected, the dropdown's value was set to -1.  We were checking if the value was empty.  -1 was not empty, so we were filtering by a vocab named -1.
2. When a vocab was selected, we got a list of tagged terms in the vocab.  That list was filtered by the content_type option.  (Can you see where this is going yet?)  When content type was 'all', we were looking for nodes of type 'all'.

Tested against:
1. All contetn, no vocab terms.
2. Specific content, no vocab terms
3. All content, specific terms
4. Specific content, specific terms.

All four tests worked correctly.  This hsould get rid of the empty sv list issues.