Don't truncate amounts when displayed in BTC

[BTCBellyButton]

Describe the "bug" Currently the amounts shown in the transactions and utxos lists don't show trailing zeroes. It'd be nicer and easier to read if they were not truncated:

Now:

0.1234567 ($....)
0.12345678 ($....)
0.123456 ($....)

Better:

0.12345670 ($....)
0.12345678 ($....)
0.12345600 ($....)