Changed key/value type in the Thrift file from string to binary.

1) To implement Objective-C SDK, changed key and value type in the thrift file from string to binary.

2) We will store different kinds of data as a "value" in Nanolat Database. These include user pictures and any kind of binary data.

3) Also added Objective C implementation of Thrift client. These are copied from thrift source disribution version 0.9.1.