WIP: Modification for the working of social-help activity.

This PR introduces the changes required in sugar for the functioning of the social-help activity. The changes are self explanatory and I'm adding a few comments (GitHub ones) in the diiff to explain some of the things. 

This PR is a submission to one of the GSoC 2014 sugarlabs projects.

PS: I still have to run pep8 and pyflakes on all files.
Why don't we store the mappings on a json file on the server and use that file?  That would allow us to add a new forum without requiring people to update sugar (happens about once a year).