drop evs service

drop evs service

there are several reasons for this:

1) evs is only partially implemented with no plans to complete it

typedef enum {
       EVS_TYPE_UNORDERED, /* not implemented */
       EVS_TYPE_FIFO,          /* same as agreed */
       EVS_TYPE_AGREED,
       EVS_TYPE_SAFE           /* not implemented */
} evs_guarantee_t;

2) evs has no users in any upstream distribution and no search
   engine can find any other upstream using it.

3) the only reason (I was told) to carry around evs was that evs
   receives the full ring_id struct from totem. This is only
   partially correct because while the structures are prepared
   to carry around those data, they are never transmitted from
   corosync engine down the IPC line to the user.
   CPG ring_id contains the exact same information and it's
   actually less buggy (due to prototying of the info).

worst case scenario where a user really absolutely need libevs,
it can be easily reimplemented as libcpg wrapper and avoid
lots of code duplication.

Signed-off-by: Fabio M. Di Nitto <fdinitto@redhat.com>
Reviewed-by: Steven Dake <sdake@redhat.com>