Merge remote-tracking branch 'rafal-krypa/issue70' into v1.0.x
utils: use fts functions for scanning directories

The BSD functions fts_open() and fts_read() are a nice alternative
to ftw/ntfw and manual directory reading. This commit replaces existing
readdir() and nftw() usage to get:
- applying CIPSO rules in one shot, just like regular rules
- sort input files alphabetically to load them in a defined order
  (readdir() order is file system dependant)
- loading rules works on file systems not setting d_type on readdir()
  (fix 233dc30 regression)
- better performance compared to nftw() due to fewer calls to stat()
  internally
- shorter code due to unified handling of load from file and from
  directory

Signed-off-by: Rafal Krypa <r.krypa@samsung.com>