A screen's status follows its connection, and other improvements

Fixes

• A screen that had reconnected after a dropped connection could keep showing “Disconnected” on its Details tab, which also made “Power off” unavailable. The status now follows the connection.
• A reboot sent to a screen without a live connection could be lost if it arrived at the moment the screen was checking in. It now reaches the screen at its next check-in.

Improvements

• The timezone pickers in account settings and in an app’s timezone setting are searchable. Type a city, a region, or an offset instead of scrolling through around 420 zones.
• Emails from Screenly no longer start their subject line with “[Screenly]”. The sender name already says who they’re from.
• A tidier Screenshot card on a screen’s Overview, with the time under the image.