Integrate Althea DAO into Gnosis Frontend

[jtremback]

• [x] Add "Althea" item to top menu bar
• [x] Have Althea DAO just appear in there when you click it
• [x] Don't worry about having both angular and react in the app for now
• [ ] Make all the stuff in the Althea DAO work

[sbc64]

Deadline: 18/1/2019

[sbc64]

Add "Althea" item to top menu bar is done but nothing else besides that: https://github.com/sebohe/MultiSigWallet