WIP tags: REST API addition

Addition of rest api for tags.
Still work in progress.
@konstantinos1991 :warning: your code will not behave the way you intended it to :warning:

```
Python 3.4.1
>>> dict(a=1, b=2).keys()                                                                                                            
dict_keys(['b', 'a'])

Python 2.7.7
>>> dict(a=1, b=2).keys()
['a', 'b']
```