apps: Integrate tshark into the application

This is the initial prototype that generates packet trace summaries. The
current implementation parses pcap files into psml and pdml using a
ported version of tshark which runs under NaCl. It then converts the
pdml and psml into html and displays them following a format similar
to wireshark's gui.

The packet trace analyzer will be a component of the apps/logprocessor.

To use, load the app as an unpackaged app through the
chrome://extensions interface. From the app, upload a .pcap file and
the resulting summary information will be displayed.

The README includes instructions for obtaining library packages
including grunt and jasmine. Grunt is used to drive Jasmine tests.

For testing purposes, sample .pcap files are included in the
sample_files directory.

BUG=chromium:467418
TEST=manually tested on local pcap files. "grunt test" Jasmine test
cases pass.

Change-Id: Idd9f96354c6d305f8a20bb564992998638ed6c4c