Change init sequence to support file level encryption

File level encryption must get the key between mounting userdata and
calling post_fs_data when the directories are created. This requires
access to keymaster, which in turn is found from a system property.

Split property loaded into system and data, and load in right order.

Bug: 22233063
Change-Id: I409c12e3f4a8cef474eb48818e96760fe292cc49