Switch from GCC 5 that doesn't work with Eigen to 4.8

Enable mkldnn_fc for general format

Docker build: create deb file and build Go by default.

Otherwise the production image generation will fail due to deb not
found, or executable built from Go not found.

Fix some warning.

Rename PROJ_ROOT to PADDLE_SOURCE_DIR and PROJ_BINARY_ROOT to PADDLE_…

Support to create a gradient machine with merged model in c-api

related codes in Paddle core.

to create a gradient machine for inference using merged model with parameters
which is genearted by `paddle merge_model`.

Feature/fix random op link error

support python test without installation python package

Fix the bug between nvcc and boost

* Should always use `dynload::` for cuda function.
* Fix cublas.h without DSO load.

turn off with_mklml and with_mkldnn to fix ImportError of libmklml_intel.so

Fix #3386

 tensor slight improve

fix test_KmaxSeqScore for only CPU compile.