Fixed obtainment of some blocks (like default:gravel and technic:marble)

Some blocks weren't obtained by TBM. The problem was that "dropped" variable, used by "tbm.dropitem" expects information from "get_definition().drop" and some nodes don't have "drop" field on their definition table. Now there is an exception that gets the name of the block when there is no "drop" info.
Merge pull request #1 from aracnus/master

Fixed obtainment of some blocks (like default:gravel and technic:marble)