cqlsh: update recognized syntax for cql3

cqlsh should recognize cql3 syntax when in cql3 mode; this includes tab completing proper syntax and properly quoting any terms in single- or double-quotes (current version only knows how to use single quotes).

also, prefer using the term "TABLE" over "COLUMNFAMILY" wherever one of those is generated from cqlsh (like in DESCRIBE output).

and if it's not too bad, it would help to have the online help strings reflect cql3 syntax (maybe with a nod to cql2 restrictions where appropriate).