Travis CI failed offen

[ChihChengLiang]

Some builds failed with the following error message:

Error: Invalid JSON RPC response: ""

but when it happens, a rebuild is usually successful.

Travis CI 斷掉的情況相當於沒有執行 testrpc 就跑 truffle test 的情況。我的猜測是 Travis CI 有些資源限制，讓 testrpc 的 process fork 無法順利成功。但～～我對這塊不是很熟，不太知道怎麼改善