[FLINK-1203] Deactivate fork reuse in tests (workaround for potential surefire bug)

This closes #174
[FLINK-1202] Remove incomplete file outputs on failure

This closes #175
Remove obsolete collection execution example.
Correct remote collector format example.
Implement coarse-grained fault tolerance
Introduce a delay before restarts to make sure that taskmanager failures are detected before restart.
Improve error messages in case of invalid file paths or URIs

This closes #170
Make sure TaskManager does not accept task deployments when shutting down
[FLINK-1205] Fix library cache manager to track references to tasks and revent accidental duplicate registration/deregistration
[FLINK-1203] Use forked execution in all tests, except in the end-to-end integration tests in flink-tests
[FLINK-1198] Broadcast variables are shared between tasks in the same TaskManager
[FLINK-1198] Make Broadcast variables shared per taskmanager, rather than a shared singleton per JVM
             (supports multiple TaskManagers in the same JVM)
[FLINK-1198] Broadcast variables can share initialization via broadcast variable initializers
[FLINK-1198] Fix nullpointer exception in broadcast variable materialization
Make sure that operator names are properly escaped for display in the web client
Temporarily disable fork reuse in flink-tests Unit tests (workaround for FLINK-1207)
[doc] Fix programming guide link in iterations.md
[FLINK-1210] Improve error message in delta iterations when the next workset does not depend on the workset
[FLINK-1174] [streaming] Added window join operator
[streaming] Enhanced BufferTimeout functionality for StreamRecordWriter
Change TypeExtractor to support interfaces within classes

Before, the pojo analyzer would try to analyze a field of type List
or Map and fail. Now we catch the exception and create a GenericTypeInfo
for the enclosing class because the avro serializer can in fact
serialize objects that have fields of interface type.