FIX: GridField button styling

Remove all top/bottom margins from buttons and apply to GridFieldButtonRow component. Ensure that all buttons are added to a suitable GridFieldButtonRow in ModelAdmin, SecurityAdmin and Group.
Only have Scrutinizer check PHP files
Exclude docs and images foldes from Scrutinizer
Correct line length and indentation
Merge pull request #2347 from simonwelsh/3.1

Scrutinizer fixes
Only have Scrutinizer check PHP files
Exclude docs and images foldes from Scrutinizer
Correct line length and indentation
Merge pull request #2348 from simonwelsh/scrut

Scrutinizer fixes
API Provide a thin alternative to loadPanel/submitForm.

This is needed in some situations when we only want to update a
small single component, sometimes even using a different controller to
the one implied in the URL.

An example here is reloading dynamically the subsite dropdown without
reloading the entire page, updating a filter sidebar or suchlike.
Merge pull request #2352 from mateusz/loadfragment

API Provide a thin alternative to loadPanel/submitForm.
Fix Behat window switching in chrome

Workaround only, see https://groups.google.com/forum/#!topic/behat/QNhOuGHKEWI
Merge remote-tracking branch 'origin/3.0' into 3.1.0

Conflicts:
	model/Hierarchy.php
Merge remote-tracking branch 'origin/3.1.0' into 3.1

Conflicts:
	dev/BehatFixtureFactory.php
	model/Hierarchy.php
	tests/behat/features/bootstrap/FeatureContext.php
	tests/core/CoreTest.php
Fixed 3.1-specific switchToWindow() behat feature
Added link to translation CI
Return jQuery deferred object from LeftAndMain's loadFragment.
FIX Make sure that debug always shows up first
Fix typo in form method name.
Update ImagickBackend.php