Add usage manual for VisualDL, and modify four pictures in directory demo/component/usage_interface. (#549)

The usage maunal will be helpful for beginners to make use of VisualDL.

The components of ViusalDL are introduced in details,
including definitions of functions, parameters explanations.
Moreover, demos are given for each component.

The former pictures of demo are lack of some details in the frontend webpage,
I upload new pictures to make demo more intuitive.

add component usage demo

* prepare for v1.1 release

* upload missing onnx model

* Add the 'how to use embedding' tutorial

* Add the chinese version of how to use embedding doc

* update syntax

* add punctuation

* change visualdl to visualDL

* Prove reading

* prove reading

* Add a new PyTorch example to show embedding.
Update pybind document.

* Change the function of embedding to take word
dictionary.

* Simplify Paddle demo by showing vgg only and add comments

* update python format

* fix format issue

* Add license to the top of files

* Add licenses agreement on the demo files

* Provide demo code how on to create text records.

* Remove test code

* Complete audio data integration:
* Add num channels, sample width, sample rate as params
* Generate audio file with proper params

* clang format

* Adjust the sync_cycle automatically.

* Change the multiplier type to double.

* Adjust the sync_period.

* Fix comment.

* Add the pre-commit

* Run pre-commit with other files.

* Update the version number
Update the doc to include Vue
Update the doc to give more details on the sync_cycle
Update the doc to include python 3

* Update the LogWriter constructor doc.

* Update the package copy directory.

* Update the version to 0.0.2 (implying beta now)

* Update the vdl_create_scratch_log to python 3 as well.

* Display documentations of demos on the Docs.

* Rename the title from `demos` to `Examples`.

* Provide English tutorial on how to use VisualDL in Keras

* Add the English Tutorial of PyTorch.

* Add the English MXNet tutorial.

* Remove links in the MXNet tutorial.

* rename vdl_scratch.py to vdl_create_scratch_log

* Simply replace the vdl_scratch.py

* Binary Record Fixes

* Fixed issues with binary_record.h filename generator method.  std::hash is not consistent across OS.  It will generate different hash's when ran on different OS on the same string.  Change the filename generator to use a static counter.  It will be more ideal to use UUID generator available in boost 1.4.2, however, boost 1.4.2 has problems compiling on c++11 \n* Fix issue with pytorch demo where it logs to the absolute path /workspace

* Fix performance issue on server when server fails to load image file.  Currently server retries an API call 3 times before it fails, at which point it'll sleep the thread for 2 secs.  This becomes problematic when there are alot of SDK errors.  I'll create seperate issue to refine the retry logic to not be so expensive on the server.

* Add C++ and python style check to travis.  
* Update all C++/python code that violate coding standards.

* support manylinux build

* mxnet graph

* long graph

* added full graph

* add gif back

* updated gif

* fix comments

* remove python highlight for one line