Missing currency and amount (bug 906786)

Adding more logs to be able to analyze the issue with values returned
by Bango.
Merge pull request #126 from davidbgk/906786-missing-currency

Missing currency and amount (bug 906786)
explictly unset pin_was_locked_out instead of implicitly (bug 887862)
Merge pull request #127 from wraithan/bounce

explictly unset pin_was_locked_out instead of implicitly (bug 887862)
swap pending and received around (bug 888038)
Revert "swap pending and received around (bug 888038)"

This reverts commit faa1c1bef605f04c1295f233db430d68f51a93e6.
rearrange docs to match code, record errors on billing config as failed transactions (bug 888038-reboot)
no need to test the presence of missing uid_pay anymore (bug 888038)
use the external transaction id (bug 912025)
Merge pull request #129 from andymckay/912025

use the external transaction id (bug 912025)