Address foreign key issues

The other restructuring issues were:

* The authoritative table on slice existence is now slice, not storage.
  Storage can have multiple entries for an os, app, sliceid triplet.
  Slice can only have one.  Storage now has an fkey relying on slice,
  and other relationships now check for slice records instead of
  storage.
* The column "sequence_id" should be "sequenceid" to match the other
  "id" columns.
* The "slicelineage" and "netchatter" tables are now obviated.  They
  are now removed.

Also, the "regresult" table is now removed.

Signed-off-by: Alex Nelson <a.nelson@prometheuscomputing.com>