[SPARK-2317] Improve task logging.

We use TID to indicate task logging. However, TID itself does not capture stage or retries, making it harder to correlate with the application itself. This pull request changes all logging messages for tasks to include both the TID and the stage id, stage attempt, task id, and task attempt.  I've consulted various people but unfortunately this is a really hard task. 

Driver log looks like:

```
14/06/28 18:53:29 INFO DAGScheduler: Submitting 10 missing tasks from Stage 0 (MappedRDD[1] at map at <console>:13)
14/06/28 18:53:29 INFO TaskSchedulerImpl: Adding task set 0.0 with 10 tasks
14/06/28 18:53:29 INFO TaskSetManager: Re-computing pending task lists.
14/06/28 18:53:29 INFO TaskSetManager: Starting task 0.0:0.0 (TID 0, localhost, PROCESS_LOCAL, 1203 bytes, 5 ms)
14/06/28 18:53:29 INFO TaskSetManager: Starting task 0.0:1.0 (TID 1, localhost, PROCESS_LOCAL, 1203 bytes, 3 ms)
14/06/28 18:53:29 INFO TaskSetManager: Starting task 0.0:2.0 (TID 2, localhost, PROCESS_LOCAL, 1203 bytes, 3 ms)
14/06/28 18:53:29 INFO TaskSetManager: Starting task 0.0:3.0 (TID 3, localhost, PROCESS_LOCAL, 1203 bytes, 3 ms)
14/06/28 18:53:29 INFO TaskSetManager: Starting task 0.0:4.0 (TID 4, localhost, PROCESS_LOCAL, 1203 bytes, 3 ms)
14/06/28 18:53:29 INFO TaskSetManager: Starting task 0.0:5.0 (TID 5, localhost, PROCESS_LOCAL, 1203 bytes, 3 ms)
14/06/28 18:53:29 INFO TaskSetManager: Starting task 0.0:6.0 (TID 6, localhost, PROCESS_LOCAL, 1203 bytes, 3 ms)
14/06/28 18:53:29 INFO TaskSetManager: Starting task 0.0:7.0 (TID 7, localhost, PROCESS_LOCAL, 1203 bytes, 3 ms)
14/06/28 18:53:29 INFO TaskSetManager: Starting task 0.0:8.0 (TID 8, localhost, PROCESS_LOCAL, 1203 bytes, 5 ms)
14/06/28 18:53:29 INFO TaskSetManager: Finished 0.0:7.0 (TID 7) in 50 ms on localhost (1/10)
14/06/28 18:53:29 INFO TaskSetManager: Starting task 0.0:9.0 (TID 9, localhost, PROCESS_LOCAL, 1203 bytes, 4 ms)
14/06/28 18:53:29 INFO Executor: Running task 0.0:9.0 (TID 9)
14/06/28 18:53:29 INFO TaskSetManager: Finished 0.0:5.0 (TID 5) in 68 ms on localhost (2/10)
14/06/28 18:53:29 INFO TaskSetManager: Finished 0.0:6.0 (TID 6) in 70 ms on localhost (3/10)
14/06/28 18:53:29 INFO Executor: Finished task 0.0:9.0 (TID 9). 517 bytes result sent to driver
14/06/28 18:53:29 INFO TaskSetManager: Finished 0.0:4.0 (TID 4) in 80 ms on localhost (4/10)
14/06/28 18:53:29 INFO TaskSetManager: Finished 0.0:3.0 (TID 3) in 85 ms on localhost (5/10)
14/06/28 18:53:29 INFO TaskSetManager: Finished 0.0:2.0 (TID 2) in 91 ms on localhost (6/10)
14/06/28 18:53:29 INFO TaskSetManager: Finished 0.0:1.0 (TID 1) in 98 ms on localhost (7/10)
14/06/28 18:53:29 INFO TaskSetManager: Finished 0.0:0.0 (TID 0) in 109 ms on localhost (8/10)
14/06/28 18:53:29 INFO TaskSetManager: Finished 0.0:8.0 (TID 8) in 39 ms on localhost (9/10)
14/06/28 18:53:29 INFO TaskSetManager: Finished 0.0:9.0 (TID 9) in 30 ms on localhost (10/10)
```

Executor log looks like
```
14/06/28 18:53:29 INFO Executor: Running task 0.0:0.0 (TID 0)
14/06/28 18:53:29 INFO Executor: Running task 0.0:1.0 (TID 1)
14/06/28 18:53:29 INFO Executor: Running task 0.0:5.0 (TID 5)
14/06/28 18:53:29 INFO Executor: Running task 0.0:3.0 (TID 3)
14/06/28 18:53:29 INFO Executor: Running task 0.0:2.0 (TID 2)
14/06/28 18:53:29 INFO Executor: Running task 0.0:6.0 (TID 6)
14/06/28 18:53:29 INFO Executor: Running task 0.0:4.0 (TID 4)
14/06/28 18:53:29 INFO Executor: Running task 0.0:7.0 (TID 7)
14/06/28 18:53:29 INFO Executor: Finished task 0.0:0.0 (TID 0). 517 bytes result sent to driver
14/06/28 18:53:29 INFO Executor: Finished task 0.0:3.0 (TID 3). 517 bytes result sent to driver
14/06/28 18:53:29 INFO Executor: Finished task 0.0:5.0 (TID 5). 517 bytes result sent to driver
14/06/28 18:53:29 INFO Executor: Finished task 0.0:4.0 (TID 4). 517 bytes result sent to driver
14/06/28 18:53:29 INFO Executor: Finished task 0.0:1.0 (TID 1). 517 bytes result sent to driver
14/06/28 18:53:29 INFO Executor: Finished task 0.0:7.0 (TID 7). 517 bytes result sent to driver
14/06/28 18:53:29 INFO Executor: Finished task 0.0:2.0 (TID 2). 517 bytes result sent to driver
14/06/28 18:53:29 INFO Executor: Finished task 0.0:6.0 (TID 6). 517 bytes result sent to driver
14/06/28 18:53:29 INFO Executor: Running task 0.0:8.0 (TID 8)
14/06/28 18:53:29 INFO Executor: Finished task 0.0:8.0 (TID 8). 517 bytes result sent to driver
```
Another option is to just add a field `taskName` in either `TaskInfo` or `Task` itself, and just use that everywhere.