Added --localfile_path and --localfile_url to be used when --localfile is True; --localfile_path which is the file system path, and --localfile_url which defines the URL. Defaults for both of these make it work the way that it currently does (serves in current direct, with /localfile/ as URL
Addresses the issues from PR: better code for abspath, testcases for all options (none for absolute local file dir path, yet), renaming _url to _uri
Files for unittests
allow specifying the path to be served by /localfile/

with `--localfiles=PATH`
update local file handler

- remove commented-out code
- 404 on missing notebooks
- file encoding
update local files test
Merge pull request #198 from dsblank/master

add --localfiles=PATH

closes #198