Added HHVM container and used environment variable for switching

hhvm/server.ini

@@ -0,0 +1,20 @@
+; php options
+
+pid = /var/run/hhvm/pid
+
+; hhvm specific
+hhvm.server.port = 9000
+hhvm.server.type = fastcgi
+hhvm.server.default_document = index.php
+hhvm.server.error_document404 = index.php
+hhvm.server.upload.upload_max_file_size = 25M
+hhvm.log.level = Error
+hhvm.log.header = true
+hhvm.log.access[default][file] = /var/log/hhvm/access.log
+hhvm.log.access[default][format] = "%h %l %u %t \"%r\" %>s %b"
+hhvm.server.source_root=/var/www/laravel/public
+hhvm.repo.central.path = /var/run/hhvm/hhvm.hhbc
+
+; Uncomment to log to files instead of STDOUT
+;hhvm.log.use_log_file = true
+;hhvm.log.file = /var/log/hhvm/error.log