SetupBolt opens a boltdb and creates a meta bucket if not exists.
Bolt holds a pointer of bolt.DB boltdb is used to store a cache of Changelogs of Ubuntu/Debian
Close a db.
EnsureBuckets puts a Meta information and create a buket that holds changelogs.
GetChangelog get the changelgo of specified packName from the Bucket
GetMeta gets a Meta Information os the servername to boltdb.
PrettyPrint is for debug
PutChangelog put the changelgo of specified packName into the Bucket
RefreshMeta gets a Meta Information os the servername to boltdb.
Cache is a interface of cache
DB has a cache instance
Meta holds a server name, distro information of the scanned server and package information that was collected at the last scan.