Use afsd code in libuafs

Use afsd code in libuafs

Share the same CM code for the kernel client as in libuafs, so we
don't duplicate code for initializing the cache and other things. In
order to do this:

 - Remove some libuafs global variables that share name and
   functionality with those in afsd, and declare some static

 - Remove uafs_Init(), and move the ukernel-specific code in it to
   osi_Init(); replace with uafs_Setup(), uafs_ParseArgs(), and
   uafs_Run(), which just call into afsd functions

 - Remove libuafs' cache initialization code (CreateCacheFile,
   SweepAFSCache, etc); instead just use afsd's

 - Add uafs_mount(), to perform the 'mount'ing step that takes place
   in the normal kernel CM

 - Add afsd_uafs.c for the glue between afsd and libuafs

Note that this now requires libcmd for libuafs.

Change-Id: I62306a18ad255680031494caf1720b29e22856d2
Reviewed-on: http://gerrit.openafs.org/1724
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>