Refactor and documentation

* Refactored `fetch` into `getFileRecord`
* Added `controlledByDeps` to indicate if Meteor is updating the file
record for us
* Added `getCollection` this will in a minimal way insure that we have
`.collection` and return it.
* Added shortcut `isMounted` call this to make sure the file is
attached to a FS.Collection
* Deprecate `fetch`
* Deprecate `useCollection`
* Added some console output to monitor internals
* Suggest `moveTo` a way of moving a file from one collectionFS to
another if allowed?
* Added in code documentation
update docs