camput: Skip base directories where IsIgnoredFile() returns true.

camput currently panics if a base directory is ignored.  Fixes issue 314.

Change-Id: I9466b4576b1134994e5e53e1067e0435ddba0fdf
Merge "camput: Skip base directories where IsIgnoredFile() returns true."
C: add Aaron Racine (Google CLA)

Change-Id: I74507840247790509a53082513e577617fa12858