Rename PlagiarismDetector to SimilarityDetector

Also rename detectPlagiarism() to detectSimilarity()

Signed-off-by: Matthew Heon <matthew.heon@gmail.com>
Cause common code detection to only be performed using Linecompare

Signed-off-by: Matthew Heon <matthew.heon@gmail.com>
Small changes to Common Code Remover to provide better logging

Signed-off-by: Matthew Heon <matthew.heon@gmail.com>