v4.7.0

• #837 Fix passing options to all_organizations
• #841 Add new methods from the most recent org memberships API enhancements
• #851 Fix application requests for non dotcom hosts
• #858 Don't mutate the options variable passed to API calls
• #871 Add support to prerelease Integrations API
• #874 Handle PR Review errors
• #860 Implement Review Preview API
• #869 Use Organization.path for organization membership method
• #880 Fix incorrect mimetype for integrations in PREVIEW_TYPES
• #881 Change several occurrences of Hash#merge!