Replace nonce cache with a ping-pong bloom filter (#1282)

* Add Ping-Pong bloom filter

* Refine bloom filter insertion

* Reduce the error rate to 0.00001

* Avoid alignment issue in murmurhash2

* Fix a memory leak

* Fix build on non-GPU targets

* Detect get_current_dir_name in configure

* Update README.md

* Remove redudant bfree()

* Reduce the memory usage for local client

* Fix #1275

* Refine #1275

* Use IP when bypassing SNI domains

* Also apply replay detector on UDP traffic

* Update deb build script

Now build script is able to auto detect system and choose libraries
necessary to build.

Also update the README accordingly.

* Update build script to enable jessie/stretch etc

Also include a few cleanup that simplified pkg installation from
backports repository.

.gitmodules

@@ -6,3 +6,7 @@
 	path = libipset
 	url = https://github.com/shadowsocks/ipset.git
     ignore = dirty
+[submodule "libbloom"]
+	path = libbloom
+	url = https://github.com/shadowsocks/libbloom.git
+    ignore = dirty