graph: Fix Cayley integration

[lmars]

The following needs to be fixed:

• support nanosecond precision in the tests here (this is why the TestSQLBackend/qs/load_typed_quad fails)
• update OpIsTrue to handle the fact that SQLite does not have a built-in 'true' literal (the vendored cayley currently has OpIsTrue set to IS 1, but upstream it is IS true
• add a SQLite regex extension so that the REGEXP operator works (this is why TestSQLBackend/qs/paths fails)
• update cayley so that it supports creating indexes in the CREATE TABLE statement (currently we are just not creating the indexes by setting NoForeignKeys)