Information in the progress window (example: rescan) is displayed capped to fixed size instead of contents.

<img width="209" alt="screenshot 2018-12-21 at 14 58 20" src="https://user-images.githubusercontent.com/26601261/50345943-0bbd4300-0531-11e9-9c6c-e277ac69eb0c.png">

switch (blockSource) {
        case BlockSource::NETWORK:
            if (header) {
                updateHeadersSyncProgressLabel();
                return;
            }
            progressBarLabel->setText(tr("Synchronizing with network..."));
            updateHeadersSyncProgressLabel();
            break;
        case BlockSource::DISK:
            if (header) {
                progressBarLabel->setText(tr("Indexing blocks on disk..."));
            } else {
                progressBarLabel->setText(tr("Processing blocks on disk..."));
            }
            break;
        case BlockSource::REINDEX:
            progressBarLabel->setText(tr("Reindexing blocks on disk..."));
            break;
        case BlockSource::NONE:
            if (header) {