Record request reason in the db instead of logging

server/a_server-packr.go

server/handlers.go

server/signer/signer.go

server/static/js/table.js

server/store/a_store-packr.go

server/store/mem.go

server/store/migrations/mysql/20180822204521_add_reason.sql

...er/store/migrations/sqlite3/20180822204521_add_reason.sql

server/store/sqldb.go

server/store/store.go

server/store/store_test.go

server/templates/certs.go