add politeia welcome page

[dreacot]

Currently on the proposals page, proposals are being downloaded automatically.

What is expected is that when the user accesses the Proposals page for the first time, they should see a welcome screen just like the StakeShuffle page, with a button at the bottom asking if they will like to download proposals.

Only then are the proposals to be downloaded based on the users consent.

[Fegor-Clinton]

Okay, that sounds right, I will work on getting this page done.