Fix #661. The input values were added to the exported tx json in commit 922b133, and are looked for when tx are read from files.  Given the values were added for offline signing, and were not present otherwise, this fix handles their non-presence on tx file import.
Fix #661. The input values were added to the exported tx json in commit 922b133, and are looked for when tx are read from files.  Given the values were added for offline signing, and were not present otherwise, this fix handles their non-presence on tx file import.

fyookball/electrum,fyookball/electrum,fyookball/electrum