Throw error requiring jade in favor of then-jade

"jade" is more popular (and more stable) than "then-jade", so we should encourage people to use that.  When neither "jade", nor "then-jade" are installed, consolidate currently throws an error asking for "then-jade".  This changes it so the error asks for "jade".

See https://github.com/balderdashy/sails/issues/1629 and https://github.com/then/then-jade/issues/9 for the confusion the error created.

P.S. I maintain "then-jade" and "jade", so have no personal bias to declare.