Fix wrap-format-params for CoyoteInputStream.

Hi Nils,

I'm running my Ring application inside Immutant/Tomcat. There the
call wrap-format-params fails because the (> (.available body) 0)
predicate is somehow false. The call to (.available body) on an
org.apache.catalina.connector.CoyoteInputStream returns 0. I'm
not sure if this is correct.

However, I looked at other middleware like ring-json. They don't
do such a check on the input stream and just slurp it. This patch
removes the (> (.available body) 0) check in order to get
ring-middleware-format working on Immutant/Tomcat.

Would you like to merge this into master and make a release?

Thanks, Roman.