Replace all .'s in app name with _ for database name

Currently only the first `.` in app name is replaced with an `_` for the database name, which results in a mongo error along the lines of `Error: [staging_exampleapp.com-production] is not a valid database name at src/mongo/shell/mongo.js:40
exception: connect failed`

Updated the mongodb_database regex to replace all .'s, so `APP=staging.exampleapp.com` becomes `staging_exampleapp_com-production`