Added custom apache conf with allow overrides enabled

I tried the new mod_rewrite module and realized that the default apache conf has allowoverride none set which prevents .htaccess file from overriding the conf file. This prevents docker wordpress from being able to have rewrite urls. With this change you can now choose the rewrite option and it will write to it with the other pull request and this will make them work.

I copied the default file in the first commit exactly and then added a section in it with allowoverride all.

What do you think @patocox?