Merge branch 'optimize-sum-seq-pooling-op' of ssh://github.com/jacquesqiao/Paddle into cpu-for-1.1-merge

close UT about dist ctr, will fix it later
test=develop

Merge branch 'dist-table-do-not-init-on-trainer' of ssh://github.com/jacquesqiao/Paddle into cpu-for-1.1-merge

Merge branch 'add-flag-to-control-rpc-thread-num' of ssh://github.com/jacquesqiao/Paddle into cpu-for-1.1-merge

Merge branch 'fix_lookuptable_in_reduce' of https://github.com/seiriosPlus/Paddle into cpu-for-1.1-merge

* fix graph num hang test=develop

* re-enable tests test=develop

* re-enable graph num check test=develop

* fix multi device pass role check test=develop

test=develop

Refine detection mAP in metrics.py.

test=develop

[1.1] remove unused code in paddle_inference_api.h

[1.1] fix python encoding problem in wmt16 related test

Add sequence_reverse_op

[1.1] fix erase end in generate proposals op

[1.1] Make reshape_op reuse input.

[1.1] Fix ubuntu dockerfile

Unify API of mixed_vector in GPU and CPU