Make change address for imported keys the same

Fixes #769
Fixed Line input
add missing @hook in exch plugin
Update itbit/coindesk exchange rate api

itbit/coindesk exchange rate requires separate API calls per currency
Moved the calls to when the exchange rate plugin updates and when the
user modifies a selection instead of every time the program needs to
query the current exchange rate

This fixes an issue with slow response time in the send tab with the
exchange rate plugin turned on and set to coindesk or itbit
revert commit 3863ee
Multiline Address error on do_send()
separate get_errors instead of raising an exception
Update plugin modules in setup.py