Updating Site Reports documentation to show the Silverstripe 3.1 method of adding custom reports.
Site Reports documentation fix

Fixing typo in Site Reports documentation. Adding more detail to Custom Report example.
Improve .htaccess commenting

Done alongside improvements of the execution-pipeline.md docs.
Installer comment taken from d5723f7.
BUG Security::findAnAdministrator doesn't always find an admin
Added 3.1.8 changelog
Merge remote-tracking branch 'origin/3.1.8' into 3.1
Update index.md
Merge pull request #3643 from chillu/pulls/htaccess-doc

Improve .htaccess commenting
Adding appropriate nginx fastcgi buffer config required for admin
Merge pull request #3626 from 3Dgoo/feature/site-reports-doc-fix

Updating Site Reports documentation
Update javascript.md fixes #3652

I needed to know how to do this to do some jQuery manipulation in the CMS.
MINOR: Fix broken 'Insert From CMS' layout

Some updates to UploadField styles broke the layout of this form a bit
Merge pull request #3656 from halkyon/nginx_buffers

Adding appropriate nginx fastcgi buffer config required for admin
Merge pull request #3645 from jonom/insert-from-styles

MINOR: Fix broken 'Insert From CMS' layout
Update csv-import.md

Translated the German to English to match up other areas in document
Merge pull request #3659 from phillprice/patch-6

Update csv-import.md
API Allow CMS re-authentication to be completely disabled if necessary
Update DropdownField.php

Update to DropdownField::create, and in one instance set the Empty Title on the instantiation, rather than afterwards.
Merge pull request #3668 from phillprice/patch-7

Update DropdownField.php
Merge pull request #3665 from tractorcow/pulls/3.1/disable-auth

API Allow CMS re-authentication to be completely disabled if necessary