SPARK-1094 Support MiMa for reporting binary compatibility accross versions.

This adds some changes on top of the initial work by @scrapcodes in #20:

The goal here is to do automated checking of Spark commits to determine whether they break binary compatibility.

1. Special case for inner classes of package-private objects.
2. Made tools classes accessible when running `spark-class`.
3. Made some declared types in MLLib more general.
4. Various other improvements to exclude-generation script.
5. In-code documentation.

Author: Patrick Wendell <pwendell@gmail.com>
Author: Prashant Sharma <prashant.s@imaginea.com>
Author: Prashant Sharma <scrapcodes@gmail.com>

Closes #207 from pwendell/mima and squashes the following commits:

22ae267 [Patrick Wendell] New binary changes after upmerge
6c2030d [Patrick Wendell] Merge remote-tracking branch 'apache/master' into mima
3666cf1 [Patrick Wendell] Minor style change
0e0f570 [Patrick Wendell] Small fix and removing directory listings
647c547 [Patrick Wendell] Reveiw feedback.
c39f3b5 [Patrick Wendell] Some enhancements to binary checking.
4c771e0 [Prashant Sharma] Added a tool to generate mima excludes and also adapted build to pick automatically.
b551519 [Prashant Sharma] adding a new exclude after rebasing with master
651844c [Prashant Sharma] Support MiMa for reporting binary compatibility accross versions.
SPARK-1128: set hadoop task properties when constructing HadoopRDD

https://spark-project.atlassian.net/browse/SPARK-1128

The task properties are not set when constructing HadoopRDD in current implementation, this may limit the implementation based on

```
mapred.tip.id
mapred.task.id
mapred.task.is.map
mapred.task.partition
mapred.job.id
```

This patch also contains a small fix  in createJobID (SparkHadoopWriter.scala), where the current implementation actually is not using time parameter

Author: CodingCat <zhunansjtu@gmail.com>
Author: Nan Zhu <CodingCat@users.noreply.github.com>

Closes #101 from CodingCat/SPARK-1128 and squashes the following commits:

ed0980f [CodingCat] make SparkHiveHadoopWriter belongs to spark package
5b1ad7d [CodingCat] move SparkHiveHadoopWriter to org.apache.spark package
258f92c [CodingCat] code cleanup
af88939 [CodingCat] update the comments and permission of SparkHadoopWriter
9bd1fe3 [CodingCat] move configuration for jobConf to HadoopRDD
b7bdfa5 [Nan Zhu] style fix
a3153a8 [Nan Zhu] style fix
c3258d2 [CodingCat] set hadoop task properties while using InputFormat
Unify the logic for column pruning, projection, and filtering of table scans.

This removes duplicated logic, dead code and casting when planning parquet table scans and hive table scans.

Other changes:
 - Fix tests now that we are doing a better job of column pruning (i.e., since pruning predicates are applied before we even start scanning tuples, columns required by these predicates do not need to be included in the output of the scan unless they are also included in the final output of this logical plan fragment).
 - Add rule to simplify trivial filters.  This was required to avoid `WHERE false` from getting pushed into table scans, since `HiveTableScan` (reasonably) refuses to apply partition pruning predicates to non-partitioned tables.

Author: Michael Armbrust <michael@databricks.com>

Closes #213 from marmbrus/strategyCleanup and squashes the following commits:

48ce403 [Michael Armbrust] Move one more bit of parquet stuff into the core SQLContext.
834ce08 [Michael Armbrust] Address comments.
0f2c6f5 [Michael Armbrust] Unify the logic for column pruning, projection, and filtering of table scans for both Hive and Parquet relations.  Fix tests now that we are doing a better job of column pruning.
SPARK-1286: Make usage of spark-env.sh idempotent

Various spark scripts load spark-env.sh. This can cause growth of any variables that may be appended to (SPARK_CLASSPATH, SPARK_REPL_OPTS) and it makes the precedence order for options specified in spark-env.sh less clear.

One use-case for the latter is that we want to set options from the command-line of spark-shell, but these options will be overridden by subsequent loading of spark-env.sh. If we were to load the spark-env.sh first and then set our command-line options, we could guarantee correct precedence order.

Note that we use SPARK_CONF_DIR if available to support the sbin/ scripts, which always set this variable from sbin/spark-config.sh. Otherwise, we default to the ../conf/ as usual.

Author: Aaron Davidson <aaron@databricks.com>

Closes #184 from aarondav/idem and squashes the following commits:

e291f91 [Aaron Davidson] Use "private" variables in load-spark-env.sh
8da8360 [Aaron Davidson] Add .sh extension to load-spark-env.sh
93a2471 [Aaron Davidson] SPARK-1286: Make usage of spark-env.sh idempotent
Add more hive compatability tests to whitelist

Author: Michael Armbrust <michael@databricks.com>

Closes #220 from marmbrus/moreTests and squashes the following commits:

223ec35 [Michael Armbrust] Blacklist machine specific test
9c966cc [Michael Armbrust] add more hive compatability tests to whitelist
SPARK-1316. Remove use of Commons IO

(This follows from a side point on SPARK-1133, in discussion of the PR: https://github.com/apache/spark/pull/164 )

Commons IO is barely used in the project, and can easily be replaced with equivalent calls to Guava or the existing Spark `Utils.scala` class.

Removing a dependency feels good, and this one in particular can get a little problematic since Hadoop uses it too.

Author: Sean Owen <sowen@cloudera.com>

Closes #226 from srowen/SPARK-1316 and squashes the following commits:

21efef3 [Sean Owen] Remove use of Commons IO
Initial experimentation with Travis CI configuration