language changes: remaining uses of ~[T] are now replaced with Vec<T>.

In particular, this commit changes the API of `Cursor::get_column_names`
and `Cursor::get_blob`. The test for the latter has been added.
Merge pull request #78 from lifthrasiir/de-uniqvec

Language changes: Remaining uses of ~[T] are now replaced with Vec<T>.
remove ~-strings
compile the tests too