add 'returning' method, to specify return value, fixes #18
don't null the transaction until it's completed flushing
Merge branch 'master' of github.com:tgriesser/knex

* 'master' of github.com:tgriesser/knex:
  throw helpful exception when you mistype the client
minor tweak to error wording
correct call for base query flush
lowercasing when
restore basic raw binding support, needs refactor