script to check softwares are installed or not, before trying out tutorial

[gaurav-dalvi]

before we do run make demo-*, a single script to check following :

1: Check whether you have vagrant installer or not. (version > some basic working version of vagrant say 1.8.x) 2: Check whether you have installed Virtualbox or not ? 3: Check whether you have installed docker-engine and its running or not. 4: Check if git is present or not.