SPARK-1925: Replace '&' with '&&'

JIRA: https://issues.apache.org/jira/browse/SPARK-1925

Author: zsxwing <zsxwing@gmail.com>

Closes #879 from zsxwing/SPARK-1925 and squashes the following commits:

5cf5a6d [zsxwing] SPARK-1925: Replace '&' with '&&'

(cherry picked from commit cb7fe5034826844f1b50fbe8b92646317b66f21c)
Signed-off-by: Reynold Xin <rxin@apache.org>
[SPARK-1931] Reconstruct routing tables in Graph.partitionBy

905173df57b90f90ebafb22e43f55164445330e6 introduced a bug in partitionBy where, after repartitioning the edges, it reuses the VertexRDD without updating the routing tables to reflect the new edge layout. Subsequent accesses of the triplets contain nulls for many vertex properties.

This commit adds a test for this bug and fixes it by introducing `VertexRDD#withEdges` and calling it in `partitionBy`.

Author: Ankur Dave <ankurdave@gmail.com>

Closes #885 from ankurdave/SPARK-1931 and squashes the following commits:

3930cdd [Ankur Dave] Note how to set up VertexRDD for efficient joins
9bdbaa4 [Ankur Dave] [SPARK-1931] Reconstruct routing tables in Graph.partitionBy

(cherry picked from commit 56c771cb2d00a5843c391ae6561536ee46e535d4)
Signed-off-by: Reynold Xin <rxin@apache.org>
Updated dev Python scripts to make them PEP8 compliant.

Author: Reynold Xin <rxin@apache.org>

Closes #875 from rxin/pep8-dev-scripts and squashes the following commits:

04b084f [Reynold Xin] Made dev Python scripts PEP8 compliant.

(cherry picked from commit 9ed37190f45fd9e6aa0f2c73b66d317732a53eb8)
Signed-off-by: Reynold Xin <rxin@apache.org>
SPARK-1933: Throw a more meaningful exception when a directory is passed to addJar/addFile.

https://issues.apache.org/jira/browse/SPARK-1933

Author: Reynold Xin <rxin@apache.org>

Closes #888 from rxin/addfile and squashes the following commits:

8c402a3 [Reynold Xin] Updated comment.
ff6c162 [Reynold Xin] SPARK-1933: Throw a more meaningful exception when a directory is passed to addJar/addFile.

(cherry picked from commit 90e281b55aecbfbe4431ac582311d5790fe7aad3)
Signed-off-by: Reynold Xin <rxin@apache.org>
SPARK-1932: Fix race conditions in onReceiveCallback and cachedPeers

`var cachedPeers: Seq[BlockManagerId] = null` is used in `def replicate(blockId: BlockId, data: ByteBuffer, level: StorageLevel)` without proper protection.

There are two place will call `replicate(blockId, bytesAfterPut, level)`
* https://github.com/apache/spark/blob/17f3075bc4aa8cbed165f7b367f70e84b1bc8db9/core/src/main/scala/org/apache/spark/storage/BlockManager.scala#L644 runs in `connectionManager.futureExecContext`
* https://github.com/apache/spark/blob/17f3075bc4aa8cbed165f7b367f70e84b1bc8db9/core/src/main/scala/org/apache/spark/storage/BlockManager.scala#L752 `doPut` runs in `connectionManager.handleMessageExecutor`. `org.apache.spark.storage.BlockManagerWorker` calls `blockManager.putBytes` in `connectionManager.handleMessageExecutor`.

As they run in different `Executor`s, this is a race condition which may cause the memory pointed by `cachedPeers` is not correct even if `cachedPeers != null`.

The race condition of `onReceiveCallback` is that it's set in `BlockManagerWorker` but read in a different thread in `ConnectionManager.handleMessageExecutor`.

Author: zsxwing <zsxwing@gmail.com>

Closes #887 from zsxwing/SPARK-1932 and squashes the following commits:

524f69c [zsxwing] SPARK-1932: Fix race conditions in onReceiveCallback and cachedPeers

(cherry picked from commit 549830b0db2c8b069391224f3a73bb0d7f397f71)
Signed-off-by: Aaron Davidson <aaron@databricks.com>