buffer-hashmap v0.1.1

Implement hashmap on buffer,uses Buffer as its storage space rather than heap memory

eg. var map = require("buffer-hashmap").createMap({type:'UInt64'},{userId:{type:'UInt64'},title:{type:'String',maxLength:10}},20000); map.set(1000,{userId:30,title:"test"}); map.get(1000);

TODO: Buffer length limit in v8(2GB on 64 bit,1GB on 32 bit), union buffer to support more. support array as value.