Reformat code
Merge branches 'master' and 'sng2c' of https://github.com/carpedm20/korail2 into sng2c
add raising NoResultsError in search_train()
add raising NoResultsError after filtering in search_train_* functions
fix bug
add error code 'WRD000061' to NoResultsError
Merge pull request #18 from carpedm20/sng2c

Reformat source code based on PEP