Add INSERT, DELETE features to osquery

Add INSERT, DELETE features to osquery

- DELETE statement logic -
If the statement has a where clause, xFilter is called.
(otherwise, xUpdate is called directly.)
And xFilter calls VirtualTable::generate to find row matched with
the where clause.
When the row comes out, execute the delete statement through xUpdate.

Signed-off-by: Sangwan Kwon <sangwan.kwon@samsung.com>