Reorganized the environments page to flow better.

- Added details about how to set the environment for an application
- Added details about setting the environment for Oil

Signed-off-by: Zechariah Campbell <zech.campbell@gmail.com>
Clarified the number of methods to set environment
Merge pull request #651 from zechdc/1.8/develop

Reorganized the environments page to flow better.
added an nginx example; corrected windows commandline example
updated the Parser docs
documented the File::download inline feature
added an nginx example config; closes fuel/core#1716
Fix coding style
Merge pull request #652 from kenjis/patch-1

Fix coding style
本家変更分をmerge