Stopped usage of Index.isForeignKey()
Updated meta data versions, and protobuf related files
removal of index.constraint field
Removal of DDLGenerator
minor clean-up
Update on comments, removed Schema parameter from Index.isConnectedToFK(), removed one unused case handling Primary Indexes
Fixed tests, that don't end on IT
Fixed tests, that don't end on IT
merge SytzeH: Removal of index.constraint field, and DDLGenerator()

Merge pull request #1360 from SytzeH/sql-layer/indexCon
https://github.com/FoundationDB/sql-layer/pull/1360