Geonames OpenPolis API support with REDIS cache!

* REDO external resource backends API and settings!

* first try :)
* install requirements (redis python module) and redis server
* needs syncdb
* needs update settings
Support for query strings in external resource urls
Cache clean method
Sligth updated to Geoname model
First integration of django-ajax-selects for geonames

https://github.com/crucialfelix/django-ajax-selects

NEEDS SETTINGS AND URL UPDATE
Rewied implementation about the ActionRequest handling.

* removed 'user' parameter from the post_action_status_update signal provided args
* removed spam decorators from the views which do not regard the Action directly
* now the forms modify instance variables instead of class variables
* removed user_profile.html template
* refactored: recipient --> recipient_set (fk --> m2m)
* modified ActionRequest handling implementation:
    * if a request is processe, all the requests which are duplicates of the former are automatically processed as well
    * so, the first processed request send a notice to the ActionRequest sender, while all the duplicates raise a "requestAlreadyAccepted" exception whether a referrer tries to process it another time
* modified private message implementation:
    * a pm is sent from a user top the all the action referrers.
* fixed bad assert (it does not raised an exception before)
* implemented a check to raise a ParanoidException if the user who is processing an ActionRequest is not among its recipents
* a new Activity is registered after status change request from an Action referrer to the Staff

p.s. this will be the last massive commit, I swear :)
Constants refactored, modified a view comment.
Refactored urls (fixed url names conflicts).
Action threshold and ready status

* implemented new exception
* now ready status is correctly set automatically when the status property is accessed, the threshold was computed and the Action is not victorious or closed
* tests passed
User profile view

* fixed query to retrieve actions in askbot_extensions/models.py
* commented views, urls refactoring
* tests work
Updated TODO
Interface between openaction and openpolis API to link geonames to actions.

This commit has the only purpose to share the changes.
Everything has still to be tested.
Added instructions to link the INSTALLED_APPS to the Askbot installation.
Set pk for looked up elements
Ajax_select_field implementation to add/update Action Geoname objects (locations).

* Implemented views and dedicated lookup channel
* tested
Server side (partial) implementation of the politicians.

The steps to follow are:
    * check that the total threshold coming with the form data is equal to the sum of all the threshold delta of the chosen politicians
    * finally get politician data from backend to create Politician objects in the db
Fixed some bugs on the politician linkage to the Action.
Fixed remaining bugs on the Politician linkage to the Action.

* server side code is tested
* deleted 'birth_date' attribute from Politician
* code cleaned from prints
HUGE refactoring of geonames form POST processing

cleaned some code :) done together with Matteo and Dominique
Added new methods extending exceptions, but they do not seem to work. Exceptions are raised directly where needed.