* Because currently Paddle only use protobuf 3.

test_rest_hook.py => test_reset_hook.py

Change-Id: I84909ade4a1ea2bec4311264626dd000cd6bc86c

To solve this, we maintain the list of DefaultNameFactory used in by trainer_config_helper,
and reset the state at the beginning of each parse_config call.

Change-Id: I13c7574dc8f0b6bc6f6b7c92eb425e2c52c926e8

* Make float equal works well.
  * compare 0.01 and 0.009999999999 will return true.

* Fix lots of trainer_config_helpers bug, and complete unittest for `layers.py`

Change cos_sim to use CosSimLayer layer when size=1 and rename convex_comb_layer to linear_comb_layer

Also add an unittest for layers.py, currently for a few things. More need to be added later.