Master dev kit (#163)

* DevKit updates

* DevKit updates

Author: ElectricMaxxx

Makefile

@@ -24,7 +24,6 @@ ifdef BRANCH
 	VERSION=dev-${BRANCH}
 endif
 PACKAGE=symfony-cmf/tree-browser-bundle
-
 list:
 	@echo 'test:                    will run all tests'
 	@echo 'unit_tests:               will run unit tests only'

README.md

@@ -21,7 +21,7 @@ The TreeBrowserBundle provides tree navigation for the Content Repository.
 ## Requirements
 
 * PHP 5.6 / 7.0 / 7.1
-* Symfony 2.8 / 3.1 / 3.2 / 3.3
+* Symfony 2.8 / 3.1 / 3.2 / 3.3 / ^3.4@dev
 * See also the `require` section of [composer.json](composer.json)
 
 ## Documentation