Groups TOSDR API calls in a mediator function

Groups all TOSDR API calls in a seperate TosdrMediator function. This is
a refactoring and does not change any behaviour.
Fix URLs
Refactor TOSDR API calls
Update XPI
Merge branch 'cimm-tosdr-mediator'
Extract service update logic

Extracts the service update logic to a seperate function so the
`main.js` file does not need to calculate dates, it can simply ask the
UpdateTracker if it needs to fetch the updated services list.
Merge pull request #22 from cimm/update-tracker

Refactor service update logic
Fix rendering data in popup
Show "not rated" panel
Fix service link id on tosdr.org
Notify only with classes higher than D
update XPI
Merge branch 'clarkbw-master'
Bug fixes with addon update

- update version to 0.4.
- Replace ss.storage.services with tosdrServices to prevent conflict
with 0.4.
- Change urlbarbutton and panel IDs to prevent conflict with old panel.
Remove tosdr_mediator

- use https:// for API.
- Add @clarkbw && @cimm to contributors.