Move color-pallete above bootstrap include

This allows us to properly override variables used by bootstrap
Moves gateway-list div into gateways.html
Large re-org of the manage currencies system

This commit extracts 3 new controllers, plus one service from what was
the ManageCurrenciesCtrl.  We have now added the AddGatewayCtrl, the
GatewayListCtrl and the GatewayListItemCtrl.  The added service is named
Gateways and is used to actually manipulate your trustlines and wallet.
Remove unused var
Fixes busted link in gateway list
Merge pull request #724 from stellar/mc-notifications

Large re-org of the manage currencies system