H2 in-memory db für unit tests hinzugefügt

pom.xml

src/main/java/edu/hsh/dbs2/imdb/logic/GenreManager.java

src/main/java/edu/hsh/dbs2/imdb/logic/Manager.java

src/main/java/edu/hsh/dbs2/imdb/logic/MovieManager.java

src/main/java/edu/hsh/dbs2/imdb/logic/PersonManager.java

src/test/java/edu/hsh/dbs2/imdb/TestDB.java

src/test/resources/META-INF/persistence.xml