Intermediate commit to save changes for other work. 
Get ColumnEquivalenceFinder to add FK joins to equivlence list. But is
too aggressive. And GroupJoinFinder needs to use Equivs to find joins
properly.
Merge branch 'foreignkey-use-join' into find-fks-layered
Update the ColumnEquivelenceFinder to find more/better potential
equivelences by looking throught the FKs for all of the tables used in
the query. 

This enhances the group join finder, which in turn makes the
JoinAndIndexPicker more capable of finding joins to select. 

Add to the RulesTests for this enhancement.
Minor cleanup and optimization to check fewer FKs.
Reduce number of FKs to check

Add two (non-functional) tests for large processing used in
verification.
Split the Equivalencies into two (column and FK), adding the former to
the latter for finding FK joins, and the former left alone for general
processing. 

Add test case as explained by Merge comments to ensure correct
processing.
Add Long test tat now passes.
Update the ColumnEquivalenceFinder to handle two cases: child table with
no declared primary key, and subqueries getting the FKs Equivs
correctly.

Add test for same from Hibernate.
merge tjoneslo: Large query part 3: Expand column equivalents

Merge pull request #1197 from tjoneslo/sql-layer/find-fks-layered
https://github.com/FoundationDB/sql-layer/pull/1197