Move functions in cryptohome_util into a set of new files

To clarify what's left in CryptohomeLibrary.

BUG=141016
TEST=none
R=hashimoto@chromium.org

Review URL: https://codereview.chromium.org/25435005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226682 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226682