Added test to ensure that we can delete more than 1000 nodes.

In sqlite there is a hard limit to the number of records which can be
selected with the "IN(x, x, x ...)" syntax which previously caused
operations like this to fail.
fix deleting more than 1000 nodes on sqlite
Merge pull request #149 from jackalope/test_deletion_of_morethan_thousand_nodes

Deletion of more than 1000 nodes on sqlite