Revert "Remove posting functionality"

I'll try to validate that this works so people can actually
use c4 instead of just lurk like I do (´･ω･`)

This reverts commit 00b2c47c31a1d4a0f570be4cc94d022b39b6669a.
Fix missing spoiler label
Fix posting replies

Resto wasn't set because I apparently changed threadId -> thread-no,
without changing the form template. whoops.
Release v0.2

Update readme with clearer install instructions.