prepare 4.0.0-alpha.1 (#566)

* changed CHANGLOG format

CONTRIBUTING.md

@@ -21,4 +21,4 @@ If you are uncertain about any part or need help please feel free to ask for hel
 * A pull request should be mergeable (fast-forward) if not, you will be asked to update it.
 * Ideally any change should include updated or new unittests to cover the changes. You can submit a PR without tests, but it will take longer to merge as someone else will need to fix the test coverage.
 * Solarium follows the Symfony2 code standards: http://symfony.com/doc/current/contributing/code/standards.html
-* Each PR will be checked by the CI environment automatically. Ofcourse anything other than a 'green' status needs to be fixed before a PR can be merged.
+* Each PR will be checked by the CI environment automatically. Of course anything other than a 'green' status needs to be fixed before a PR can be merged.

composer.json

@@ -28,11 +28,6 @@
     "config": {
         "sort-packages": true
     },
-    "extra": {
-        "branch-alias": {
-            "dev-develop": "4.0.x-dev"
-        }
-    },
     "autoload": {
         "psr-4": {
             "Solarium\\": "src/"