Clean up file drop and processing

Add status
Clear button
Button enable/disable control
Adds max number of files per zip archive

Generates downloads for sequentially number archive parts.

Some other cleanups.
Small cleanups, disable buttons during processing
Generate zipfile async so status can be updated.
Use generator/consumer model for processing entries

Make status messages appear correctly.
Can be extended to allow cancel button.
Add a final message when zip is complete
Merge branch 'fileGenerator' into gh-pages

This improves the feedback while files are being scanned.

* fileGenerator:
  Add a final message when zip is complete
  Use generator/consumer model for processing entries
  Generate zipfile async so status can be updated.
Adds filePath support

Now can add optional filePath to the processor function
of the file reader utility (allows mapping of directory
names to dicom tag values in mapDom).
very explicit commenting of hashUIDx
more comments based on tests
add file path parsing