[WIP] refactoring the code to make the CLI easily available

[vincentsarago]

This PR does:

• move cli to scripts/cli.py
• add version directly in setup.py
• couple style formatting in cog_tiles.py
• add entry_points in setup.py

To Do

• [x] update doc
• [x] update changelog
• [x] create version 1.1.0

cc @normanb

[normanb]

Looks great! I pulled the code and tested it and it works for me.