FIX Only block root vendor folder

Use RewriteRule instead to take in account any subfolder via RewriteBase. Deny ss-cache and composer via RewriteRule too.
Add code-sniffs other than line length to scrutinizer
Merge pull request #1934 from simonwelsh/scrut

Add code-sniffs other than line length to scrutinizer
BUG GridFieldFilterHeader works without non-filterable cols

Previously relied on the presence of a last column which wasn't filterable,
commonly a GridFieldEditButton. If this wasn't present, the filter buttons
were never added, leading to the GridField JS reload request being sent
without the required button form action, so GridFieldFilterHeader->handleAction()
was never called.
Update server-requirements.md
Update common-problems.md
Update common-problems.md
Update common-problems.md
Merge pull request #1982 from chillu/pulls/gridfield-filter-cols

BUG GridFieldFilterHeader works without non-filterable cols
Merge pull request #1786 from colymba/3.0-htaccess-fix

vendor folder is blocked only if outside themes
Updated translations
Behat: New fixture notation in "manage files" tests
Behat: Support for TreeDropdownField
Behat fixture refactoring (shared factory instance)
Behat: Copy fixture identifier to "Name" or "Title" by default

This makes fixture setup less verbose, particularly for behat
tests (e.g. with "Given a page 'About Us'")
Behat: Use explicit fixtures
Behat: Backport improved dropdown step handler
MINOR: equality check consistency

Updated all equality logic checks to use double == for consistency across the page.
Merge pull request #2069 from stevie-mayhew/patch-1

MINOR: equality check consistency
Test $allowed_actions on controllers with template name=action conventions