Transaction support

[vonagam]

Support transactions with same format as feathers-knex (params.transaction.trx).

Hooks can easily be moved too (mainly this line need change from Model.transaction to Model.knex().transaction and removal of debug lines), but i do not have tests for them.

[mcchrish]

I think we would also want to check that the data isn't saved in the database before the commit.

[vonagam]

Ok, tried to add checks for this. There is a problem.
You need to have multiple connections to db for that.
And sqlite have problems with it: 1, 2.
Simple addition of pool: { min: 2, max: 2 } makes tests on my machine run 14s against usual 4s and sometimes some random test will fail with "database is locked"...

So it seems it does not worth the trouble, but just to be clear this one is passing with pool 2:

it('works with commit', () => {
  return people.create({ name: 'Commit' }, { transaction }).then((data) => {
    return people.find({ query: { name: 'Commit' } }).then((data) => expect(data.length).to.equal(0)).then(() => {
      return transaction.trx.commit().then(() => {
        return people.find({ query: { name: 'Commit' } }).then((data) => expect(data.length).to.equal(1))
      })
    })
  })
})

[mcchrish]

LGTM