Set up basic extension

* added .gitignore
* added manifest.json
* added 128x128 icon
* added vendor direcotry (added .gitkeep)
Added content script for navigation

* changed manifest.json
* added content script css
Added navigation bar

* added graphics for background and shadow
* added graphics to web_accessible_resources in manifest.json
Added navigation

* added graphics for buildings
* changed css
Bump version number to 0.1.0
Merge branch 'release/0.1.0' into develop