Created ProtoTest.ProtoAST namespace to store all ProtoAST related testcases

Moved relevant testcases to ProtoTest.ProtoAST
Added class declaration AST testcases

1. class declaration AST, generate code and execute code testcases
2. class declaration AST, execute AST testcases
Merge pull request #102 from junmendoza/NodeToCode_Branch

Created ProtoTest.ProtoAST namespace to store all ProtoAST related testc...