grid reducer
chained mapreduce, basic types
a basis for the clusterisation class
Merge branch 'master' into simplified-mapred

Conflicts:
	src/main/java/pl/edu/agh/student/offlinedstream/Coordinates.java
	src/main/java/pl/edu/agh/student/offlinedstream/Grid.java
	src/main/java/pl/edu/agh/student/offlinedstream/OffDstream.java
	src/main/java/pl/edu/agh/student/offlinedstream/OffDstreamMapper.java
	src/main/java/pl/edu/agh/student/offlinedstream/OffDstreamReducer.java