Improved installation documentation (#263)

* Added Steps for Installing VirtualBox on Windows

VirtualBox is an easy, robust way to install Origami easily on Windows. I myself find it extremely useful, and these are just preliminary steps to setting up an Ubuntu virtual machine for Origami.

* Instructions for Ubuntu Virtual Machine & Edits

What was included:
- Hyper-V removal instructions
- Ten steps on setting up an Ubuntu virtual machine
- Edits to the installation of VirtualBox.

* Instructions for installing Docker

* Installation of Yarn, Pip, Python, and Node

* Extensive changes & added steps

Added further documentation on specific installation steps. This should make installing easier with more steps and concise commands.

* Shortening README

Drop-downs were used to make the README more brief and can be expanded at will.

* Removed Step 8 from V.E. instructions

* Fixing Travis Build Issue by Updating .travis.yml

Making Python versions the same as in the latest branch.

.travis.yml

@@ -3,7 +3,7 @@ language: python
 
 python:
   - "2.7"
-  - "3.4"
+  - "3.6"
 
 addons:
   postgresql: "9.5"