feature #850 Update SE for Symfony 3.0 (fabpot)

This PR was merged into the 3.0-dev branch.

Discussion
----------

Update SE for Symfony 3.0

Commits
-------

dcf4ead move sessions outside of the cache directory
693e1f7 moved to the 3.0 directory structure
4a86c13 removed obsolete files
43e379e updated deps to make it possible to install SE with Symfony 3.0

Author: fabpot

.gitignore

@@ -1,11 +1,12 @@
-/web/bundles/
-/app/bootstrap.php.cache
-/app/cache/*
 /app/config/parameters.yml
-/app/logs/*
-!app/cache/.gitkeep
-!app/logs/.gitkeep
-/app/phpunit.xml
 /build/
+/phpunit.xml
+/var/bootstrap.php.cache
+/var/cache/*
+!var/cache/.gitkeep
+/var/logs/*
+!var/logs/.gitkeep
+/var/sessions/*
+!var/sessions/.gitkeep
 /vendor/
-/composer.phar
+/web/bundles/