Added NestedColumnFilter, not used yet.

Change-Id: I15c93e6177817638babc310615ee71ca71cc7e6b
WhereClause can now be built with nested column filtering logic.

Change-Id: I738c56fa7ed454fbff0edda2b9b30cc3445e02ff
simplified column filtering code
adjusted the nested column filter request
added error checking/reporting
Merge branch 'aws-release' of https://github.com/IVPR/Weave into aws-release
Merge branch 'master' of https://github.com/IVPR/Weave into aws-release
fixed bug in NestedColumnFilters.assertValid()
Merge branch 'master' of https://github.com/IVPR/Weave into aws-release
more error checking
Merge branch 'master' of https://github.com/IVPR/Weave into aws-release
fixed nested filter bugs
Merge branch 'aws-release' of https://github.com/IVPR/Weave into aws-release