changing the signature to IObservable

probably a nasty threading bug in there that I need to eliminate later
targeting output folder
adding rx to acceptance tests
making IEventStream completely async
asynced all the things
Persistence store commit returns null fix, passing test added. Simulates pipeline pre-commit hook returning a false.
moving this api over to observables
Merge branch 'observable' into mergeobservable

Conflicts:
	.gitignore
	src/NEventStore.Persistence.PostgreSql.Tests/packages.config
Compilation fix after merge. (Fix needs to be re-analyzed for blocking call)
missing await
Remove unused type
Make class internal, don't want to spam people's intellisense
Extension method to have a nicer way to timeout a task
Remove unused type.
Remove remaining IDbStatement non-async methods and drop 'Async' suffix.
Remove unused type
Remove duplicate test. Rename some local variables in the remaining one.
Remove a test that had been commented out. Dispatcher is gone and this one tested transaction spanning them.
Await the async operations in order for the try catch block to be usable.
Await operations so the try-catch has an opportunity to be invoked.