Remove unused cost parameter in ParameterUpdater

change float to real in two tests

support UBUNTU MIRROR and modify doc

Cmrnorm

Matrix API refactor

Add const in ParameterUpdater init

Change float in test_ConvTrans and test_ConvUnify to real.

Add excluded_chunk_types to ChunkEvaluator

The chunks of types in excluded_chunk_types will not be counted in
ChunkEvaluator. This is useful for tasks such as SRL, in which chunks of
type V (verb) will not be taken into account in evaluation.

Add unittest to cover SgdThreadUpdater's enableBufType

Synchronic code from PaddlePaddle/Paddle

reference or raw matrix (Matrix & or Matrix *)
contextProjectionForward
contextProjectionBackward
contextProjectionBackwardData
contextProjectionBackwardWeight
classificationError
The mul functions would be updated later.

fix typo: you -> we

fix dead links and refine tutorials/index

Fix RNN unittest bugs.

Added support for cudnn v6 and cuda 8.0

Clean BatchNorm Code.

add cluster_train_cn.md

refine data_sources.py and PyDataProvider2.py to make more readable