move elasticsearch/elasticsearch dependency to dev requirements

composer.json

@@ -13,13 +13,16 @@
     "require": {
         "php": ">=5.6",
         "symfony/serializer": "~2.7|~3.0",
-        "paragonie/random_compat": "^1.0|^2.0",
-        "elasticsearch/elasticsearch": "~5.0"
+        "paragonie/random_compat": "^1.0|^2.0"
     },
     "require-dev": {
         "phpunit/phpunit": "~5.6",
         "squizlabs/php_codesniffer": "~2.0",
-        "satooshi/php-coveralls": "~1.0"
+        "satooshi/php-coveralls": "~1.0",
+        "elasticsearch/elasticsearch": "~5.0"
+    },
+    "suggest": {
+        "elasticsearch/elasticsearch": "This library is for elasticsearch/elasticsearch client to enhance it with DSL functionality."
     },
     "autoload": {
         "psr-4": {