Updated requirements in composer.json to "~3.1" to support 3.1.0 stable.

See https://groups.google.com/forum/#!topic/silverstripe-dev/kCHSHLZp2Yg
Merge pull request #49 from purplespider/patch-1

Updated requirements in composer.json to "~3.1" to support 3.1.0 stable.
API bulk manager actions are now editable

Bulk actions can now be added/removed via component's addBulkAction()
and removeBulkAction()
API bulk action front-end data are configurable

Bulk action front-end behaviour and style can now be configured via
array( 'isAjax' => true, 'icon' => 'accept', 'isDestructive' => false )
passed to addBulkAction()
FIX Refactor JS bulk action handling

JS bulk action handling now works for any custom action
API bulk actions use separate handlers

Bulk actions are now handled by separate classes and should extend
GridFieldBulkActionHandler. Bulk action matching should be defined in
$url_handlers
Bulk editing is now separated from main logic

Created separate handler and js
Added proper visual clues about updated records
FIX action btn + loading indicator

.doBulkActionButton btn doesn't trigger cms actions and now has loading
indicator
Update readme
FIX added destructive action confim dialog
FIX: Bulk editing now works with multiple grid fields and managers on the page

Removed use of ID in JS
FIX: Removed ID on select all checkbox
Merge pull request #52 from mi3ll/patch-1

FIX: Bulk editing now works with multiple grid fields and managers on the page
FIX check records selection first + spinner timing

Check if anything is selected first + fix start spinner titming
FIX #53 removed type hinting for scalar
German translation
Merge pull request #55 from wernerkrauss/germantranslation

German translation
Added Czech translation
FIX bulkaction finally take care of  url variables properly