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.
We don't need check the json file every time. Store the last time you downloaded it, and use a configuration to define how many days until the next check. Other than that, I agree.