Mark DEPRECATED and set EXPIRATION_DATE (2017-03-01)
There is only one port (sysutils/fusefs-rar2fs) that depends on this and it
is currently BROKEN. However, there is an update in the works to fix it
and make it work with the newly added archivers/libunrar5. We already have
archivers/libunrar (3.x) and archivers/libunrar5 as it is.

Add CONFLICTS_INSTALL with the other libunrar ports.