v2.0.0 Beta 4

• Fixes issue with deep listener paths - #219, #221
• Fix race condition with uniqueSet - #207
• react v16.0.0-0 added to peer dependencies
• presence and sessions options support passing a function:

  {
    userProfile: 'users',
    // list of online users organize by group parameter
    presence: (user) => `presence/${user.group}`,
    sessions: (user) => `sessions/${user.group}`
  }

• sessions option can now be set to null to not writing user sessions when using presence
• Removed unnecessary constructor from FirebaseConnect component
• combineReducers is now internal instead of being imported from redux (shrinks bundle size and limits dependencies)
• Webpack updated to v3.4.1
• Material-UI example updates (Navbar state uses auth state instead of profile state)
• Usage of profileFactory is wrapped in try/catch to handle and reject errors within provided factory function