Implement hash and isEqual: methods.
Improve hash by including the isset values.
2654435761 is the NSNumber hash for 1.
Merge branch 'master' into hash_isequal

Conflicts:
	compiler/cpp/src/generate/t_cocoa_generator.cc
Merge pull request #7 from dwnld/hash_isequal

Fix merge of THRIFT-2897 branch.