travis: use longer timeout
travis: use longer timeout

sometimes the unittest fails due to 120s timeout. The travis-ci might
be overloaded? Let's see what happens with the longer timeout.

Signed-off-by: FUJITA Tomonori <93dac1fe9c4b2a3957982200319981492ad4976e@gmail.com>

j-kato/gobgp,fujita/gobgp,a16/gobgp,osrg/gobgp,j-kato/gobgp,a16/gobgp,osrg/gobgp,j-kato/gobgp,fujita/gobgp,a16/gobgp,fujita/gobgp,a16/gobgp,fujita/gobgp,osrg/gobgp,a16/gobgp,osrg/gobgp,a16/gobgp,a16/gobgp