Bug: ExpiryTooFar should be detected

[C-Otto]

Describe the bug
When sending out a payment with a "total time lock" exceeding the configured value for max-cltv-expiry, the SendToRoute invocation fails. This error is not detected/logged.

To Reproduce
Send a payment through nodes with high CLTV delta values.

Expected behavior
The error is logged/shown to the user.

[C-Otto]

This is related to #38. The information shown to the user is provided via PaymentStatus, whereas the actual payment loop uses PaymentInformation in MultiPathPaymentObserver. Non-final errors, including the common "temporary channel failure", are not provided to PaymentStatus.