Simple oasis setup for project.

Very simple setup using oasis for building.

Because it's using corebuild it has a problem with non-exhaustive pattern matches. I haven't understood enough of the code to make confident fixes for those issues. 

```
➜  ocaml-memcached git:(oasis_setup) make 
ocaml setup.ml -build 
Finished, 1 target (0 cached) in 00:00:00.
+ /Users/tim/.opam/system/bin/ocamlfind ocamlc -c -g -thread -package async -package bitstring -syntax camlp4o -package bitstring.syntax -package core -o memcached.cmo memcached.ml
File "memcached.ml", line 263, characters 24-304:
Warning 8: this pattern-matching is not exhaustive.
Here is an example of a value that is not matched:
7
File "memcached.ml", line 299, characters 27-58:
Warning 8: this pattern-matching is not exhaustive.
Here is an example of a value that is not matched:
1
File "memcached.ml", line 331, characters 8-30:
Error: Unbound value Char.code
Command exited with code 2.
Compilation unsuccessful after building 4 targets (0 cached) in 00:00:02.
E: Failure("Command ''/usr/local/bin/ocamlbuild' memcached.cma memcached.cmxa memcached.a memcached.cmxs -tag debug' terminated with error code 10")
make: *** [build] Error 1
```

Loving the write-ups on your blog and reddit/r/ocaml :+1: