feat(splitter): chunking projectid, vaultid, start_marker and end_marker

This patch allows every vaultid specific to a projectid to be chunked
with a start marker and end marker. This allows the manager to be
instantiated with a different start and end marker when calling the
validation functions.

Addresses Issue: https://github.com/rackerlabs/deuce-valere/issues/10
I would advise looking further into this and ensuring that it splits the data correctly.

If start/end are the same, then it will not look at anything since the conditions would not work.

Duplicates okay - just means we may do more work than necessary, though race-conditions could be encountered depending on the scheduling. Perhaps using a set() would be better than a list() to help manager that?