NewClient sets up Client.

DBPath is the location of the bolt DB.

SessionBucket is the name of the bolt bucket that stores sessions.

UserBucket is the name of the bolt bucket that stores the users.

ErrExists means the value was found in the DB.

ErrNotFound means the requested key could not be found in DB.

Client is a client to the bolt DB.

DBClient is the interface that gets implemented by this package.