Merge pull request #6 from k-hotta/master

a pull request at the end of the implementation of MethodAnalyzer
remove unused test cases
implement a function to detect pairs of revisions
create a class to calculate similarities of given pairs of strings
create a class to represent a table
implement a function to detect pairs of methods
create a table for vector pairs in db
create a data class for a pair of vectors
create a registerer for VectorPairData
create a retriever for VectorPairData
[REFACTORING] rename VectorPairRegisterer into VectorPairDataRegisterer