init test framework

[Superjomn]

fixes: #521

[dzhwinter]

Only change the grammar?

[dzhwinter]

Please dismiss the previous Approve, it's a mistake click.

[kavyasrinet]

I have a bunch of rephrasing comments, maybe once the other reviewers approve this PR, we can merge this and I can create a new PR with the suggested rephrasing and you folks can review it. I was trying to point them out here, but there are quite a few of them, so I stopped at two.

[kavyasrinet]

"Models continuous integration" => "Continuous integration for models"

[kavyasrinet]

"based on" => "using"

[wanghaoshuang]

As a supplement:
We should make standards for feeding arguments to model trainning.
e.g. ：save_dir_path of 'generate_chinese_poetry' is different with model_save_dir of 'text_classification'.

Furthermore, building models bank as a python module may be helpful for implementing test framework conveniently. After pip install paddle-models-versionxxx we can use models as below:

import paddle.models
model = models.text_classification()
arguments = {'batch_size': 128, 'train_passes':500 ...}
model.setArgs(arguments)
model.train()