Description of the issue/feature this PR addresses:

This pull request aims to improve upon the structure, readability*, and completeness of the installation guide.

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      -  It is overly explicit and assumes nothing about the users level of experience —or familiarity with tech, until after the Packaged Installer methods.

      -  The Demo and SaaS sections are more sales slanted, as there could be small business owners trying to make a go of Odoo on their own.

      -  Removes references to limitations, where they are unhelpful: "Odoo has no limitations" :: wink ::

      -  It's conversational and inviting, until after the Windows Packaged Installer methods, with the goal of signaling Small Business owners: "we're helpful and friendly.. Call us and we wont talk over your head.."

      -  Signals to Developers that Odoo might be an easier FOSS to work with: "it's obviously committed to documentation... And it's explicit?!?"

      -  It makes a point to avoid contractions and confusing idioms, where possible in order to aid translation/readability (i.e., you're to you are; je m'appelle to je me apelle)

      -  Strips some industry jargon/acronyms or approaches them more friendly ―potential customers, "I can do this"; developers, "I don't know x or y, but I could use this and contribute z..."
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- See below... 

Is Your Business Writing Too Smart for Its Own Good?
http://www.printwand.com/blog/is-your-business-writing-too-smart-for-its-own-good

How to Write for an Eighth-Grade Reading Level
http://www.proedit.com/how-to-write-for-an-eighth-grade-reading-level/

Current behavior before PR:
Flesch-Kincaid Grade Level, SMOG, Coleman Liau Avg: 12th Grade

Desired behavior after PR is merged:
It's not ready to be merged. Just looking for guidance:

Flesch Kincaid Grade Level: 9th Grade
Flesch Kincaid Reading Ease: +11 points

I confirm I have signed the CLA and read the PR guidelines at www.odoo.com/submit-pr
Cody Kitterman