Issues with wash on node.js

[rpaquay]

• When listing entries of the node filesystem, we should skip entries we can't read instead of exiting wash with a fatal error.
• We don't convert fs.Stats into StatResult properly: size and mode are not converted appropriately
• We append too many / at the start of paths.
• On Windows, ls nodefs:/ list all the file/directories of the root directory of the current drive. We should probably list all drive letters instead.

[rpaquay]

Potential workaround on the last issue:

http://stackoverflow.com/questions/12622758/list-partitions-in-nodejs