Added support for Personal accounts

Fixes #5 

I've added basic support for a personal iDoneThis account. No account type switching, yet. I've also renamed `project` to `team` everwhere in the code, as this is more consistent with IDoneThis' own naming conventions.

In order to use this, you need to update your config with a new setting `account_type`. Set this to either `personal` or `team`. If you set it to `personal`, you can leave `team` empty (it will be ignored anyway). You'll also need to rename the old `project` setting to `team`.