Update src/DataCacheBehaviorQueryBuilderModifier.php

Use `json_encode` instead of `serialize` because it is 2x faster and requires less memory.

see http://stackoverflow.com/questions/804045/preferred-method-to-store-php-arrays-json-encode-vs-serialize
Merge remote-tracking branch 'staabm/patch-1'

Conflicts:
	src/DataCacheBehaviorQueryBuilderModifier.php