Hotfix for unix timestamp handling & bigint value casting

• filter widget needs to handle value casting for BigIntegerField type fields
• unix timestamp support was failing in annotation building on generic sql driver

Metabase 0.9

• several charting improvements (tooltips, better axis calculations, bug fixes)
• unix timestamps can now be used as if they are normal DateTime fields
• ability to order queries on aggregated columns
• fields can be marked as "sensitive" and won't be returned in query results
• new layout for the entire application
• single tenant model throughout the codebase
• simplified permission model which only supports Public & Private options
• new database schema metadata editing interface
• new installation flow that is shorter and simpler