Globally configurable default modes for overwrite / output directory behavior.
Configurable behavior for FileOutputFormat through regular parameters, rather than configuration.

fix yarn copyright
adopted hadoop configuration for hadoop 2.2.0

Add accumulators to web interface

Conflicts:
	stratosphere-core/src/main/java/eu/stratosphere/configuration/ConfigConstants.java
	README.md

extended pact-client to nicely support remote execution.

Reworked hardware configuration factory.

- Unified config to stratosphere-conf.yaml, which replaces the old
  nephele-user.xml and pact-user.xml and is also read by
  bin/nephele-config.sh

- Removed some settings from config:
    * instance configuration
    * multicast for broadcast
    * profiler impl classes
    * jobclient.polling.interval (adjusted default from 5 to 2)
    * pact.runtime.fs_timeout

Fixed Local Executor.
Fixed Bug in Delimited Input Formats.
Reworked KMeans tests (both single step and iterative).

Removed Pact Testing Framework for now.

Reworked Nephele Mini Cluster.
Added Local Executor.