Add "Info" view

[ScottWales]

The "Info" view provides a number of useful bits of metadata that are handy to know but unlikely to be searched for. This is just a plain view onto the Metadata table.

Use like:

import clef.db
import clef.model as cm

clef.db.connect()
s = clef.db.Session()

r = (s.query(cm.Path.path.label('path'), 
             cm.Info)
     .join(cm.Info)
     .first())
    
print(r.path, r.Info.title, r.Info.contact)

See #37