Currently, a few of the graph KVStore methods take the
`batch.SchedulerOptions` param. This is only used to set the LazyAdd
option. A SchedulerOption is a functional option that takes a
`batch.Request` which has bolt-specific fields in it. This commit
restructures things a bit such that the `batch.Request` type is no
longer part of the `batch.SchedulerOptions` - this will make it easier
to implement the graph store with a different DB backend.
Elle Mouton
11b27f07da