Rework the Taskmanager to a slot based model and remove legacy cloud code

Squashed commit of the following:

  - Post merge cleanup
  - Renamed fractionMemory into memoryFraction.
  - Removed Local and QueueScheduler and replaced it instead with an unified DefaultScheduler.
  - Removed Local and ClusterManager and inserted instead an unified DefaultInstanceManager.
  - Removed connection IDs from execution edges
  - Removed InstanceType, InstanceRequestMap, InstanceTypeDescription, InstanceTypeDescriptionTypeFactory, PendingRequestsMap
  - Fixed problems with test cases.
  - introduced simple slot system for scheduling.
  - Removed subtasks per instance
  - Added registerTaskManager to the JobManager RPC calls. RegisterTaskManager is called only once where the hardware description information is sent.

Add: Merging cloudmodel remove with new network stack
Cleanup of merge with slot-based scheduler branch.
Removed RuntimeEnvironment instantiation from execution graph construction. Removed legacy job vertex classes and input/output tasks.
Added failing behavior to JobManager if it is still in scheduled or created state
New test case: Exception during ExecutionGraph construction in the JobManager
Removed checkConfiguration method from AbstractJobVertex because it is not needed anymore
Replaced Tarjan's algorithm with a simpler depth-first traversal cycle detection algorithm. By doing so, one gets rid off a possible linear time check whether a node is contained in the stack.
Streamlined job graph algorithms to get rid off linear contains operations.
Standardized creation of input and output channels in InputGate and OutputGate. Removed linear contains check in InputGate for channels.
Merge fix to omit input/output registering on JobManager
Rework Invokable Task Hierarchy
Add some options for slot-based scheduling and changed default parallelism to one.
[FLINK-962] Initial import of documentation from website into source code (closes #34)
Add script to merge pull requests
Show version information including commit date in TaskMgr log
Add garbage collector stats to output of TaskManager memory usage debug thread
Revert unintentional change in 1357ea3a40f747e4e51b5b52612323fe55747da7
[FLINK-979] Fix NetworkThroughput test input and output task config

- Set DummyInputFormat and DummyOutputFormat via TaskConfig to respect task
  hierarchy refactoring.
- Run test via main method instead of JUnit test runner (this was originally
  a test in order to use RecordAPITestBase for JobGraph submission).

This closes #41.
[FLINK-980] Fix buffer leak in OutputChannel
Changed default number of task slots per machine to one.
Add logging for task slots.
LocalExecutor automatically picks up the maximum DOP for plans as its number of slots.
[FLINK-973] [FLINK-969] Unify, clean up, and extend all environment logging at JobManager/TaskManager startup

This closes #40.
[FLINK-926] Add shallow copy, deep equality, and hashCode to Tuple classes

This closes #17.