Make timeouts more conservative.

Otherwise, some modules fail with Exception('Invalid head of packet').
flash_finish: Recognize alternative response.

ESP8266EX module (ESP-03) consistently returns "\x01\x06", different firmwares
work as expected, so just recognize it as successful status.
write_flash: Allow to specify any numbers of address/filename pairs.

This allows to flash a typical firmware consisting of at least 2 parts in
one go, without need to power-cycle module between parts.
Add "run" command to run application in flash.

Useful to run existing application (without flashing new) when module
is started in bootloader mode. Implemented as dummy flash begin followed
by flash end.
Merge pull request #5 from pfalcon/4upstream

Few fixes and improvements for reliability/usability