Summoner 1.4

Updated the Rune and Mastery structs to match new changes in Summoner-v1.4. These include dropping strings (name, description, tier) from the Summoner API and moving them into static data where they can be localized.

Breaking changes include:
* Renaming `Talent` to `Mastery`
* Removing `Rune` struct and using `RuneId` in `RuneSlot` instead
* The field removals listed above

This is related to #24