self_update 0.8.0

Self updates for standalone executables
Documentation
# Changelog

## [Unreleased]
### Added
### Changed
### Removed

## [0.7.0]
### Added
### Changed
- accept `auth_token` in `Update` to allow obtaining releases from private GitHub repos
- use GitHub api url instead of browser url to download assets so that auth can be used for private repos
- accept headers in `Download` that can be used in GET request to download url (required for passing in auth token for private GitHub repos)
### Removed

## [0.6.0]
### Added
### Changed
- use indicatif instead of pbr
- update to rust 2018
- determine target arch at build time
### Removed


## [0.5.1]
### Added
- expose a more detailed `GitHubUpdateStatus`

### Changed
### Removed


## [0.5.0]
### Added
- zip archive support
- option to extract a single file

### Changed
- renamed github-updater `bin_path_in_tarball` to `bin_path_in_archive`

### Removed


## [0.4.5]
### Added
- freebsd support

### Changed

### Removed


## [0.4.4]
### Added

### Changed
- bump reqwest

### Removed


## [0.4.3]
### Added

### Changed
- Update readme - mention `trust` for producing releases
- Update `version` module docs

### Removed
- `macro` module is no longer public
    - `cargo_crate_version!` is still exported


## [0.4.2]
### Added
- `version` module for comparing semver tags more explicitly

### Changed
- Add deprecation warning for replacing `should_update` with `version::bump_is_compatible`
- Update the github `update` method to display the compatibility of new release versions.

### Removed