Status bar: Add missing localization strings and improve code
Status bar: Add missing localization strings and improve code

The amount of unconfirmed and unmatured coins was not a localizable
string, this has been fixed. The code has also slightly improved by
using a string join to build the final string instead of adding
spaces in the parts of the string.

fyookball/electrum,fyookball/electrum,fyookball/electrum