Add instructions for installing consistent shell across operating systems.

[ns-rse]

Further to #9, both Linux and OSX are bundled with terminals/shells (Bash) that will work with the training material. It is better to try and preempt the problems that may arise from variation, to which end the Setup instructions need augmenting.

Windows

M$-Win however has a crude command-prompt with its own language.

In order to make life simpler and have one set of instructions that work across all operating systems we will have to include instructions for Windows users to install Git for Windows which includes a Bash shell. We can use the section described in the Software Carpentry : Unix Shell - Summary & Setup for Windows which links to Windows instructions.

OSX

We may wish to also link to instructions for Bash under OSX (see the OSX tab) as the default is ZSH (which will likely work, I use ZSH all the time under GNU/Linux and the instructions work).

Linux

Bash is the default on Linux, but users may use something else (personally I use ZSH, there is KSH, FISH and more). We should to link to instructions for Bash under Linux (see the Linux tab).