Test configuration:
{
"name": "Test escaping characters",
"cmd": "echo "Hello"; echo 'world'; "
}

Output:
$ echo "Hello"; echo 'world';
"Hello"
world

Expected:
$ echo "Hello"; echo 'world';
Hello
world

Notes:
Same result using unicode \u0022 => {"cmd": "echo \u0022Hello\u0022; echo 'world'; "}

Environment:
MacOS 10.10.5
Shuttle v1.2.7
iTerm2 Build 3.0.8
Terminal.app 2.5.3 (343.7)