Bug 1029: Remove dead code: sal-binding-spi

opendaylight/md-sal/sal-binding-spi is dead code that is not being
built and hasn't for some time.  Its complicating keeping
versions up to date and verifying that they are up to date.
If it needs to be revived in the future it can be retrieved
from git.

Change-Id: I2698f4bfa687e24e65989c1257c5f80d84ebe262
Signed-off-by: Ed Warnicke <eaw@cisco.com>
Merge "Bug 1029: Remove dead code: sal-binding-spi"