Switch from deprecated :public to :public_dir
Switch from deprecated :public to :public_dir

Silences warnings in log of the form:

  :public is no longer used to avoid overloading Module#public, use
  :public_dir instead

Change-Id: I2810d961df3b9e7963e47d1787a793f07a69cfd3
Reviewed-on: https://gerrit.causes.com/24896
Reviewed-by: Greg Hurrell <79e2475f81a6317276bf7cbb3958b20d289b78df@causes.com>
Tested-by: Greg Hurrell <79e2475f81a6317276bf7cbb3958b20d289b78df@causes.com>

causes/twigg,causes/twigg