Added development debugging "support" for Neon.

Previously, there was no convenient way (from what I saw) to debug the Neon javascript sources.  Now, you can simply set DEBUG_NEON to True so the raw Neon sources will be downloaded to the client instead of the min.  Also added soft-link to the "src" directory from static/js.

NOTE: if there already existed a simple way to switch between the source and min Neon files, please let me know.