Update nan to 1.8.4 to support iojs 2.3
Update nan to 1.8.4 to support iojs 2.3

aerospike/aerospike-client-nodejs,aerospike/aerospike-client-nodejs,jklepp-tgm/aerospike-client-nodejs,jklepp-tgm/aerospike-client-nodejs,tonypujals/aerospike-client-nodejs,tonypujals/aerospike-client-nodejs,aerospike/aerospike-client-nodejs,jklepp-tgm/aerospike-client-nodejs,jklepp-tgm/aerospike-client-nodejs,aerospike/aerospike-client-nodejs,tonypujals/aerospike-client-nodejs,jklepp-tgm/aerospike-client-nodejs,tonypujals/aerospike-client-nodejs,aerospike/aerospike-client-nodejs,tonypujals/aerospike-client-nodejs