License all remaining code MIT. Fixes #38

grunt: copy brand-overlay/* to out folder

all: remove the ghostbin brand, genercize it

js: ghostbin->spectre v2

brand: replace with generic assets

js: Ghostbin->Spectre

go.mod: override gorilla/sessions with cj123/sessions

ci: build with GO111MODULE

mod: add a module description

Make sure we include inter-ui.css

(actually, just vendor the fonts too)

css: switch body font to Inter UI from Latin Modern

all: limit expiration to two days and size to 512k, disable new accounts

css: add an announcement div style

add login/logout to session; this breaks auth tokens for now