fix all shebang to #!/usr/bin/env bash instead of #!/bin/sh

Since most scripts use the substitude techniques to get DIR
variable, it do need bash instead of sh.

需要用bash来执行DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
不能直接用sh
Merge pull request #47 from spin6lock/master

Fix the "Bad substitution" warning