Merge pull request #6 from uwbas/master

Fixed packet timestamp code by using 'raw' instead of 'show' value
Moved display filter/bpf filter to base Capture class and made lazy the default option in FileCaptures.
Added manifest.in to include config.ini
Fixed display filters in file captures
Added option to reset cap to start reading from the top.
Updated setup version
Added LayerField object to keep memory usage to a minimum
Added docsto LayerField
Updated Layer's __str__ to support LayerField objects
Fixed layer __str__ again