* Separate Developer's guide from API guide
 * Update API guide to reflect the latest changes
   mostly regarding Networks
 * Create an empty Network API guide to get filled
   with the Neutron API specification
 * Add the corresponding link to the API guide in index
 * Remove obsolete Integrator's guide

TODO: Refactor/remove/update the Integrator's Quick Installation
Guide which is now out-of-date. Sort out what we should keep and
merge them to the other guides.