apps: add log type detection for android logcat and bugreport files

Detect main subsection of Android logcat and bugreport files.  This is
the first step to processing Android logs.  Added tests for both logcat
and bugreport detection.

TEST=ran 'grunt test'
TEST=manually tested with log files for chromeos, brillo and android

Change-Id: I3bf5f4669f62c62888ff249fabe27f6de4ffe7c2
8 files changed