Import assets from geocms v1

Locales, fonts, images, stylesheets
Javascript will be refactored in angularjs so don't import them
Add dependencies+config to frontend engine

Remove Gemfile.lock as it should not be checked in inside an engine
Add some configuration to serve static templates for angular using
slim.
wip : working on angular refactoring

At this point the app should get the context from the api
show the list of layers associated.
Show a map with layers on it, and some default actions from the control
menu.
Merge all migrations

Tables and model being prefixed now and the app having evolved a lot, I
feel it's better to merge all migrations to avoid errors when creating
a new project.
Move over new elements to engine

* Basic frontend fonctionnalities in angularjs
* Turn geocms into a gem