* documents will be ready afterwards

not ready now

* Update index_en.rst

* Update index_cn.rst

* Update index_en.rst

* Update index_cn.rst

* Update index_en.rst

* update_releasenote_0428

* add new

* thorough clean

* delete_DS_Store

1. add index for all English version of "进阶使用"
2. replace legacy softlinks to howto/optimization & dev/new_op_en with original file

- delete the Models index in root index
- update models/index_en.rst

* add en index for install doc,fix some expressions

* Appendix title

* add learning_materials_en and update install doc to the latest

* Update learning_materials_en.md

* update_en_structure

* remove doc/fluid/api/.DS_Store

* Start over

* Added basic docs
Added .travis.yml
Added scripts to build documentation on the Travis.

* Disable several deploy script commend for testing.

* fixed the deploy_docs.sh script.

* Update travis.yml

* Renamed docs to doc

* update .gitignore.

* Delete .gitignore

* Update .travis.yml

* Update .travis.yml

* Update deploy_docs.sh

* Update .travis.yml

* Develop doc (#1)

* Add paddle submodule

* Update the build script.

* Update script

* Use gen_doc_lib instead.

* Move files around

* cache external

* Update submodule

* try to cache batch 1

* add test code

* Update Paddle submodule

* Update submodule

* update script to print more

* update python path

* test

* test

* test

* clean up the code

* Update Script (#2)

* add new file

* Develop doc (#3)

* Add the rest of the submodules into the system

* Provide first symlink fit a line

* Update the rest of book to symlinks

* add models submodule

* Add link for models

* Update deploy_docs