Initialized the regVal for first iteration in SGD optimizer

Ported from https://github.com/apache/incubator-spark/pull/633

In runMiniBatchSGD, the regVal (for 1st iter) should be initialized
as sum of sqrt of weights if it's L2 update; for L1 update, the same logic is followed.

It maybe not be important here for SGD since the updater doesn't take the loss
as parameter to find the new weights. But it will give us the correct history of loss.
However, for LBFGS optimizer we implemented, the correct loss with regVal is crucial to
find the new weights.

Author: DB Tsai <dbtsai@alpinenow.com>

Closes #40 from dbtsai/dbtsai-smallRegValFix and squashes the following commits:

77d47da [DB Tsai] In runMiniBatchSGD, the regVal (for 1st iter) should be initialized as sum of sqrt of weights if it's L2 update; for L1 update, the same logic is followed.
Merge the old sbt-launch-lib.bash with the new sbt-launcher jar downloading logic.

This allows developers to pass options (such as -D) to sbt.  I also modified the SparkBuild to ensure spark specific properties are propagated to forked test JVMs.

Author: Michael Armbrust <michael@databricks.com>

Closes #14 from marmbrus/sbtScripts and squashes the following commits:

c008b18 [Michael Armbrust] Merge the old sbt-launch-lib.bash with the new sbt-launcher jar downloading logic.
Update io.netty from 4.0.13 Final to 4.0.17.Final

This update contains a lot of bug fixes and some new perf improvements.
It is also binary compatible with the current 4.0.13.Final

For more information: http://netty.io/news/2014/02/25/4-0-17-Final.html

Author: Binh Nguyen <ngbinh@gmail.com>

Author: Binh Nguyen <ngbinh@gmail.com>

Closes #41 from ngbinh/master and squashes the following commits:

a9498f4 [Binh Nguyen] update io.netty to 4.0.17.Final
Remove remaining references to incubation

This removes some loose ends not caught by the other (incubating -> tlp) patches. @markhamstra this updates the version as you mentioned earlier.

Author: Patrick Wendell <pwendell@gmail.com>

Closes #51 from pwendell/tlp and squashes the following commits:

d553b1b [Patrick Wendell] Remove remaining references to incubation
SPARK-1137: Make ZK PersistenceEngine not crash for wrong serialVersionUID

Previously, ZooKeeperPersistenceEngine would crash the whole Master process if
there was stored data from a prior Spark version. Now, we just delete these files.

Author: Aaron Davidson <aaron@databricks.com>

Closes #4 from aarondav/zookeeper2 and squashes the following commits:

fa8b40f [Aaron Davidson] SPARK-1137: Make ZK PersistenceEngine not crash for wrong serialVersionUID