apps:  Update regex for DisconnectReason log lines

Update regex for processing DisconnectReason property updates to
properly track log messages.

Sample line from log:
[2015-07-16T18:29:51.680057+00:00] [00:58:33.324] WiFi mlan0 supplicant
updated DisconnectReason to 7
[2015-07-16T18:30:02.459548+00:00] [00:58:44.103] WiFi mlan0 supplicant
updated DisconnectReason to -3 (was 7)

The log line will appear in the manager summary and will be highlighted
in the log text.

BUG=chromium:511479
TEST=checked manually and ran "grunt test" with the added test

Change-Id: I451aaa20082bd753663b60abecf65aa4c12a83c1
2 files changed