TV endpoint updated

## More channels added
namely:
* Rúv íþróttir
* Stöð 2 Sport
* Stöð 2 Sport 2
* Stöð 2 Gull
* Stöð 2 Bíó
* Stöð 3
* Skjár 1

## Changed root url behaviour
`/tv` now displays information about available endpionts.

## Added integration tests
Integration test for the new channels

### Documented the endpoint
I issued a [pull request](https://github.com/kristjanmik/apis-docs/pull/5) with the documentation for this endpoint on the apis-docs repository.