Change SentenceExtractor.extract method signature
merge master
Replace extractWithoutLastSentence to extract
Remove SentenceExtractor.extractWithoutLastSentence method
Refactoring extract method
Merge branch 'refactoring-sentence-extractor' of https://github.com/takahi-i/redpen into takahi-i-refactoring-sentence-extractor

Conflicts:
	redpen-core/src/main/java/cc/redpen/parser/SentenceExtractor.java
	redpen-core/src/main/java/cc/redpen/parser/WikiParser.java
	redpen-core/src/main/java/cc/redpen/parser/markdown/ToFileContentSerializer.java
	redpen-core/src/test/java/cc/redpen/parser/SentenceExtractorTest.java
migrate DocumentValidatorException to RedPenException
code reformat