[UX] Do not block the UI when waiting for Peers or Tx confirmations
When waiting for peers:
- the little green dot should be present on all pages and turn orange with the message "connecting to the blockchain" or something
When sending a Tx:
- the user sending the Tx actually doesn't care very much about the confirmations, we should consider a Tx list showing the number of confirmations. Blocking the UI at this stage doesn't bring much. Linked to https://github.com/paritytech/fether/issues/98