Revert "Code refactoring. Improve folder structure. For better project implementation. Most hosting server have a default folder public or public_html insted of htdocs, htdocs is a exclusive folder for apache web server, for example is no the same folder in NGINX."

This reverts commit e91c2c6e.

Code refactoring. Improve folder structure. For better project implementation. Most hosting server have a default folder public or public_html insted of htdocs, htdocs is a exclusive folder for apache web server, for example is no the same folder in NGINX.

This is more secure than do the request with sensitive value like password into URL parameters.

This allow to do POST requests from another website.

Bring back the existing API and mark all the operations as deprecated.
Both the existing and the new API are documented and browsable with the
Restler API Explorer. The existing API appears under "root".

The Restler API Explorer shows the classes in the order they are added
and it's a mess if they are not sorted.

Replace the GenericApi class by two classes, Login and Status, else the
endpoints would be /generic/login and /generic/status.

Simplify the code that looks for the API classes and replace the
/contact/ and /user/ APIs by /contacts/ and /users/.