MLlib documentation fix

Fixed the documentation for that `loadLibSVMData` is changed to `loadLibSVMFile`.

Author: DB Tsai <dbtsai@alpinenow.com>

Closes #703 from dbtsai/dbtsai-docfix and squashes the following commits:

71dd508 [DB Tsai] loadLibSVMData is changed to loadLibSVMFile
(cherry picked from commit d38febee46ed156b0c8ec64757db6c290e488421)

Signed-off-by: Patrick Wendell <pwendell@gmail.com>
[SPARK-1157][MLlib] Bug fix: lossHistory should exclude rejection steps, and remove miniBatch

Getting the lossHistory from Breeze's API which already excludes the rejection steps in line search. Also, remove the miniBatch in LBFGS since those quasi-Newton methods approximate the inverse of Hessian. It doesn't make sense if the gradients are computed from a varying objective.

Author: DB Tsai <dbtsai@alpinenow.com>

Closes #582 from dbtsai/dbtsai-lbfgs-bug and squashes the following commits:

9cc6cf9 [DB Tsai] Removed the miniBatch in LBFGS.
1ba6a33 [DB Tsai] Formatting the code.
d72c679 [DB Tsai] Using Breeze's states to get the loss.
(cherry picked from commit 910a13b3c52a6309068b4997da6df6b7d6058a1b)

Signed-off-by: Patrick Wendell <pwendell@gmail.com>
Bug fix of sparse vector conversion

Fixed a small bug caused by the inconsistency of index/data array size and vector length.

Author: Funes <tianshaocun@gmail.com>
Author: funes <tianshaocun@gmail.com>

Closes #661 from funes/bugfix and squashes the following commits:

edb2b9d [funes] remove unused import
75dced3 [Funes] update test case
d129a66 [Funes] Add test for sparse breeze by vector builder
64e7198 [Funes] Copy data only when necessary
b85806c [Funes] Bug fix of sparse vector conversion
(cherry picked from commit 191279ce4edb940821d11a6b25cd33c8ad0af054)

Signed-off-by: Patrick Wendell <pwendell@gmail.com>