API method for deleting a theme
An API endpoint for installing a theme, with support for specifying a version
Better exception state handling. If the theme is already installed or deleted, don't perform the action.
API endpoint for activating a theme.
'upgrade' is now 'update'. Because we're supporting the old API call, there aren't any breaking changes.
Merge branch 'master' into theme-actions-43
WP Remote can handle WP_Error objects directly

See https://github.com/humanmade/WP-Remote-WordPress-Plugin/pull/43#discussion_r5926608
Merge pull request #43 from humanmade/theme-actions-43

API methods for installing, activating, and deleting themes