handle fancy collection names in generated JS
generate nicer temp names

In the sense that they don’t require special handling in the mongo
shell.

Also treat names starting with ‘_’ as not nice, since the shell seems
to feel that way.
cleanup in MongoDB execution and JS generation
capture the actual output path in generated JS
encapsulate temp name generation effect in the execute Task
Merge pull request #166 from mossprescott/fancy-collection-names-in-js

Improve handling of collection names in generated JS