added always checkpointing flag
Merge branch 'stage1v02' into hpi
introduced MissingNode
implemented arrayschema stub
Refactored code for checkpoint decision logic
bugfix in iterator
more testcases
Checkpoint decision is now made by the task thread itself
merge with daniel
- fixed nullpointer bug in GlobalProperites with Matthias Sax's patch
fixed CPdecision
Added some debug output
Merge branch 'marrus_checkpointing' into checkpointing

Conflicts:
	nephele/nephele-server/src/main/java/eu/stratosphere/nephele/checkpointing/CheckpointDecision.java
memory optimization for upcoming reusage of pactrecords and objectnodes
started arrayschema
Resolved conflict after merge
Refined configuration of checkpoints
Fixed two bugs related to checkpoint configuration
Fixed wrong return value of getChannelType method in AbstractGate on task managers
removed tail from ArraySchema
fixed bug/test, size of ObjectSchema was too small
continued Implementation of ArraySchema, ArrayNode returns now MissingNode instead of IndexOutOfBoundsException