Clear ddocs cache on a SetDDoc().
More info on missing ddoc/view errors.
Support log() JS function.

There's more TODO, though: this is only for map() function.
And, all logs across different buckets get intertwingled
instead of having per-bucket logs for better hostability.
Moved VERSION to main.go file.
Folded misc.go into util.go and other files.

I couldn't remember / discern whether one helper function would live
in misc.go versus in util.go, so just voting misc.go off the island to
have one arbitrary place for util/helper functions.

The idea is the util/helper functions should be generic, theoretically
useful for projects that are not necessarily cbgb.