allow a Foreign key to be nullable

All or none of the Foreign fields must be nullable
Merge pull request #278 from yesodweb/nullable-foreign-key

allow a Foreign key to be nullable
Fix casing in postgresql table creation script
Fix primary key constraint in sqlite

Only add columns specified in primary key constraint rather than all
table columns.
Merge pull request #279 from dbeacham/sqlite-primary-keys

Fix composite primary key constraint in sqlite
Merge pull request #280 from dbeacham/psql-typo

Fix casing in postgresql table creation script
version bump to 2.0.1
2.0.1 version bumps
fix haddocks
reference insertMany_ from insertMany
add maintainer
haddock working on hackage now
remove backendKeyTo/FromValues

instead assume a BackendKey is a single PersistValue
fix warnings
use Lift' for liftT
fix master

overlap with idType branch
persistent-template version 2.0.1
add .dockerignore file
support setting an idType
Fix SQL compilation errors (pinging @gregwebs)