feature(tags): add getAllAfter method on tags structure

```javascript
Tags#getAllAfter(unixTimestamp:Number) => []Record
```
feature(api): add /api/today and /api/today/human

return all tags associated with today with unix timestamps and human
timestamps respectively
refactor(api): work on copy of object rather than object itself

prevent modifying original tag objects
Merge pull request #16 from sjmarshy/feat/api/today

Feat/api/today