modify README.md

* add description
* add license section
add Install plugin and small changes.

* add Install.sketchplugin
* add Sketchbundle.json.example
* add lib.js
* add any models

* add .gitignore files
* remove LICENSE
* modify README.md
functionize install condition on plugin models.
change behaviour of run function.
Merge pull request #1 from corrupt952/develop

merge develop