Fix human dates now() staying unmodified and displayed incorrectly (bnc#880081) 

TagSupport:release() is not called between invocations by the container if tag pooling is enabled, but only on GC or invocations with different set of optional paramenters.

See https://issues.apache.org/bugzilla/show_bug.cgi?id=16001 for details.

We should check other tags later.