bugfix(radixtree_host_uri): match priority, host > uri. (apache#817)

* bugfix(radixtree_host_uri): match priority, host > uri.

Fix apache#761.

luarocks: updated dependencies of version 0.8.

bugfix: created dir for zipkin. (apache#377) (apache#378)

feature: added test cases about round-robin load balance algorithms. (a…

…pache#123)

* feature: added test cases about round-robin load balance algorithms.

* feature: added test cases about consistent hash algorithms.

luaroks: updated `lua-resty-etcd` version to 0.5.