1. fix the tainted variable 'path'
2. capitalize constants in env_config_parser
3. move constants about attribute to common utils.h

1. check whether path is empty in IsEveryFilenameValid().
2. do not print the string in IsStrLengthValid(), it's not safe.
3. make the constants about hash in recorder_manager.h.
4. initialize some variables.

2. Dump the end graph in gpu session and cu session

1. add validation for directory and filename
2. refactor the file operations about path
3. add in CMakeLists
4. add logger in nn_ops

1. add env_config_path for ms_context
2. add EnvConfigParser to parse config
3. add in CMakeLists
4. clang-format, cpplint
5. fix spelling in ms_context

Use EnvConfigParser in the constructed function of base_recorder,
when a recorder is initialized, its direcctory will be set as the
value from config file. In addition, recorder_manager will get the
'enable' from config file. If 'enable' is true and the path is not a
valid value, it will be the default value: './rdr'.