Fixes for pyserial 3.0

Pyserial 3.0 was released 2 days ago and they changed the API. This broke BrewPi. This release fixes this.

Background thread serial communication

This release moves reading from serial to a background thread. Completed lines are placed on a queue to be read form the main thread.

This greatly improves responsiveness and it fixes errors created by the tiny (4K) serial input buffer in Python from overflowing. This was the cause of the control algorithm tab often not working in the web UI.

0.4.1 Firmware update fixes

• Download photon system firmware from the last release in which it was included
• Prevent Photon from rebooting into DFU mode after flashing, which caused serial exceptions

Updates for firmware v0.4.0

• Reworked update scripts
• EEPROM reset can be triggered from web interface
• FlashDfu.py accepts directory as input
• Support for toggling devices from the device manager