Refactor Corrector and Checker classes to accept metadata file path as a parameter

src/main/java/edu/bu/LanguageCorrection/Checker.java

src/main/java/edu/bu/LanguageCorrection/Corrector.java

src/main/java/edu/bu/LanguageCorrection/MainApp.java

src/main/java/edu/bu/LanguageCorrection/crawler.java