switch to java 7
comparators for terms and their occurences
comparators as singletons
work on index merger
Merge branch 'master' of github.com:ftes/de.uni-potsdam.hpi.ir.searchengine

Conflicts:
	src/main/java/de/hpi/krestel/mySearchEngine/IndexFileHandler.java
newer junit
ignore .dat files
pulled out interfaces for testing purposes
renamed occurence -> occurrence
added logging, util, exception
added mock testing impls
fixed occurence -> occurrence
made term comparator resilient to occurences with equal term strings
work on index merger
fixed occurence -> occurrence
added index merger test