update to use pg@v1.x

add postgres as pier dependency

remove all calls to pauseDrain/resumeDrain - it is now the callers responsiblity
to call the done() callback if the client is pooled. - i'd like to add more transparent
pooling library perhaps in another patch

update tests to pass & run more synchronously
test that callback receives all arguments
adding pg to devDependencies
test with v0.10 as well