[SPARK-2384] Add tooltips to UI.

This patch adds tooltips to clarify some points of confusion in the UI.  When users mouse over some of the table headers (shuffle read, write, and input size) as well as over the "scheduler delay" metric shown for each stage, a black tool tip (see image below) pops up describing the metric in more detail.  After the tooltip mechanism is added by this commit, I imagine others may want to add more tooltips for other things in the UI, but I think this is a good starting point.

![tooltip](https://cloud.githubusercontent.com/assets/1108612/3491905/994e179e-059f-11e4-92f2-c6c12d248d81.jpg)

This looks scary-big but much of it is adding the bootstrap tool tip JavaScript.

Also I have no idea what to put for the license in tooltip (I left it the same -- the Twitter apache header) or for JQuery (left it as nothing) -- @mateiz what's the right thing here?

cc @pwendell @andrewor14 @rxin

Author: Kay Ousterhout <kayousterhout@gmail.com>

Closes #1314 from kayousterhout/tooltips and squashes the following commits:

19981b5 [Kay Ousterhout] Exclude non-licensed javascript files from style check
d9ab5a9 [Kay Ousterhout] Response to Andrew's review
7752449 [Kay Ousterhout] [SPARK-2384] Add tooltips to UI.
[STREAMING] SPARK-2343: Fix QueueInputDStream with oneAtATime false

Fix QueueInputDStream which was not removing dequeued items when used with the oneAtATime flag disabled.

Author: Manuel Laflamme <manuel.laflamme@gmail.com>

Closes #1285 from mlaflamm/spark-2343 and squashes the following commits:

61c9e38 [Manuel Laflamme] Unit tests for queue input stream
c51d029 [Manuel Laflamme] Fix QueueInputDStream with oneAtATime false
[SPARK-2417][MLlib] Fix DecisionTree tests

Fixes test failures introduced by https://github.com/apache/spark/pull/1316.

For both the regression and classification cases,
val stats is the InformationGainStats for the best tree split.
stats.predict is the predicted value for the data, before the split is made.
Since 600 of the 1,000 values generated by DecisionTreeSuite.generateCategoricalDataPoints() are 1.0 and the rest 0.0, the regression tree and classification tree both correctly predict a value of 0.6 for this data now, and the assertions have been changed to reflect that.

Author: johnnywalleye <jsondag@gmail.com>

Closes #1343 from johnnywalleye/decision-tree-tests and squashes the following commits:

ef80603 [johnnywalleye] [SPARK-2417][MLlib] Fix DecisionTree tests
SPARK-1782: svd for sparse matrix using ARPACK

copy ARPACK dsaupd/dseupd code from latest breeze
change RowMatrix to use sparse SVD
change tests for sparse SVD

All tests passed. I will run it against some large matrices.

Author: Li Pu <lpu@twitter.com>
Author: Xiangrui Meng <meng@databricks.com>
Author: Li Pu <li.pu@outlook.com>

Closes #964 from vrilleup/master and squashes the following commits:

7312ec1 [Li Pu] very minor comment fix
4c618e9 [Li Pu] Merge pull request #1 from mengxr/vrilleup-master
a461082 [Xiangrui Meng] make superscript show up correctly in doc
861ec48 [Xiangrui Meng] simplify axpy
62969fa [Xiangrui Meng] use BDV directly in symmetricEigs change the computation mode to local-svd, local-eigs, and dist-eigs update tests and docs
c273771 [Li Pu] automatically determine SVD compute mode and parameters
7148426 [Li Pu] improve RowMatrix multiply
5543cce [Li Pu] improve svd api
819824b [Li Pu] add flag for dense svd or sparse svd
eb15100 [Li Pu] fix binary compatibility
4c7aec3 [Li Pu] improve comments
e7850ed [Li Pu] use aggregate and axpy
827411b [Li Pu] fix EOF new line
9c80515 [Li Pu] use non-sparse implementation when k = n
fe983b0 [Li Pu] improve scala style
96d2ecb [Li Pu] improve eigenvalue sorting
e1db950 [Li Pu] SPARK-1782: svd for sparse matrix using ARPACK
Merge branch 'master' into issues/SPARK-2415