Add new PluralSight course

Add F# Functional Data Structures course
Merge pull request #288 from misterspeedy/gh-pages

Add new PluralSight course
Added link to Visual Studio 2013 Tools for Unity
Merge pull request #289 from gradbot/gh-pages

Added link for Visual Studio 2013 Tools for Unity
Update Linux installation instruction

Should be clearer now what version of Mono is required. Defer instructions for installing from source to good quality instructions at github.com/mono/mono.
Merge pull request #290 from rneatherway/patch-2

Update Linux installation instruction
Update index.md
Update index.md
Update index.md
Update index.md
Update index.md
Update index.md
Update default.html
Create index.md
Update index.md
Update index.md
Update index.md
Update index.md
Update index.md
Update index.md