[REFACTORING] rename csvwriter into trainingsetwriter
add methods to get revisions before/after the specified number of revision
implement a function to retrieve vector pairs in specified range of revisions
[REFACTORING] rename package
add an option to switch modes of CSVWriter
implmenent a function to retrieve revisions in specified range
implement a function to write csv file for evaluation
Merge pull request #12 from k-hotta/master

puru pull