Authored by Justin R. Miller

update changelog for 1.5.0

Changelog
---------
### 1.5.0
#### January 16, 2015
- Re-added support for Mapbox `v4` API and [access tokens](https://www.mapbox.com/developers/api/#access-tokens) (removed temporarily in `1.4.0`), which are required for new accounts.
- Added support for iOS 8's QoS on background network requests.
- Improved error handling.
- Improved localization support.
- Improved deprecation notification on some previously-removed API.
- A map view's `-setCenterCoordinate:` is no longer animated by default.
- Fixed an Auto Layout bug.
- Fixed some memory leaks.
- Performance improvements, especially to background downloading for offline use and to general disk caching.
- Clarified that only web-based tile sources are eligible for background downloading.
- Documentation improvements.
### 1.4.1
#### September 5, 2014
... ...