[FLINK-970] Adds first() operation on DataSet, UnsortedGrouping, and SortedGrouping

This closes #88
Added parameter checks and tests for first-n operator.
Excluded DataSet.first(), UnsortedGrouping.first(), and SortedGrouping.first() methods from ScalaAPICompletenessTest.
Added documentation for first-n operator.
[FLINK-1104] [streaming] Eliminated Tuple1 from connectors
[streaming] Streaming jobgraph and vertex refactor to match recent runtime changes
[streaming] added batchReduceGroup, windowReduceGroup functionality to ConnectedDataStream and GroupedConnectedDataStream
[FLINK-1102] [streaming] Projection operator added to DataStream

Conflicts:
	flink-addons/flink-streaming/flink-streaming-core/src/main/java/org/apache/flink/streaming/api/datastream/DataStream.java

Conflicts:
	flink-addons/flink-streaming/flink-streaming-core/src/main/java/org/apache/flink/streaming/api/JobGraphBuilder.java
	flink-addons/flink-streaming/flink-streaming-core/src/main/java/org/apache/flink/streaming/api/StreamConfig.java
	flink-addons/flink-streaming/flink-streaming-core/src/main/java/org/apache/flink/streaming/api/datastream/ConnectedDataStream.java
	flink-addons/flink-streaming/flink-streaming-core/src/main/java/org/apache/flink/streaming/api/datastream/DataStream.java
[streaming] Fixed InternalStateTest to avoid printouts + minor StreamVertexTest fix
[doc] [streaming] Added Twitter connector & Projection operator to docs
[FLINK-1103] [streaming] Updated WordCount example to become self-contained and removed old TestDataUtil
[FLINK-1121] [streaming] minBy and maxBy operators added to streaming api
[FLINK-1122] [streaming] Job Execution with user specified name
[streaming] Streaming packages added to flink-dist lib
Add *.log files to .gitignore
Set default log level to info in examples
[FLINK-1056] Use maven-assembly to build fat-jar in quickstarts

Also update documentation accordingly.
Fix Bug with forced repartitioning in DOP changes.
Fix error with invalid config values for degree of parallelism.
Fix race condition leading to erroneous "NoResourceAvailableException".
[FLINK-1062] Type Extraction for Lambdas

Checking for Java support

Small changes and meaningful exception for unsupported compilers

pom.xml modified to use JDT compiler

Project structure refactored, examples added

Documentation added

Quickstart adapted