refactoring due to cakephp upgrade as side effect the ajax workflow fail...

...ed, commit still contain commented code to ease review

The AJAX authentication (basic authentication) is not done in the beforeFilter of the component. Therefor we had to move the instanciation of the ProgramSpecificMongoModel in the ProgramAuthComponent->startup() as at this point, the user is authenticate.

It lead to a major refactoring, in order to unify the way ProgramSpecificMongoModel are instantiate. 

Note that in BasicAuth mode, no session is initialised. Therefore one shouldn't store there the program databaseName, but rather a controller property.

Need to make sure that the HTTP API request is not failing anymore:
1) make sure the ACL have been sync and the cache cleared on cakephp
2) logout on the browser
3) run the runActions api => works fine
4) checkout master => fail with exception in the HTTP API's response