Add delete_value pointer to backends

Signed-off-by: Michael Ikey Doherty <michael.i.doherty@intel.com>
db/memory: Add delete_value support to the backend

Signed-off-by: Michael Ikey Doherty <michael.i.doherty@intel.com>
libbuxton: Unset backend's delete_value pointer

Signed-off-by: Michael Ikey Doherty <michael.i.doherty@intel.com>
db/gdbm: Add delete_value support to the backend

Signed-off-by: Michael Ikey Doherty <michael.i.doherty@intel.com>
db: Mark data variable as unused

Signed-off-by: Michael Ikey Doherty <michael.i.doherty@intel.com>
Fix typo in documentation for notifications

Signed-off-by: Michael Ikey Doherty <michael.i.doherty@intel.com>
Fix formatting (line wrap) in bt-daemon.h

Signed-off-by: Michael Ikey Doherty <michael.i.doherty@intel.com>
libbuxton: Add buxton_client_delete_value function

This is mapped back to the backend in the same way as our other
value functions. Currently not yet implemented via the wire
protocol.

Signed-off-by: Michael Ikey Doherty <michael.i.doherty@intel.com>
cli: Add delete-value command

Signed-off-by: Michael Ikey Doherty <michael.i.doherty@intel.com>
cli: Fix formatting and c_delete_value help string

delete-value, being a longer string, requires more room to ensure
the help alignment is correct.

Signed-off-by: Michael Ikey Doherty <michael.i.doherty@intel.com>
shared/client: Ensure we free BuxtonString

Signed-off-by: Michael Ikey Doherty <michael.i.doherty@intel.com>
shared/client: Fix line wrap in header

Signed-off-by: Michael Ikey Doherty <michael.i.doherty@intel.com>
protocol: Fix line wrap in header

Signed-off-by: Michael Ikey Doherty <michael.i.doherty@intel.com>
protocol: Implement buxton_wire_delete_value

Note that this is not yet implemented on the daemon side, so will
harmlessly return.

Signed-off-by: Michael Ikey Doherty <michael.i.doherty@intel.com>
libbuxton: Hand off delete_value via wire protocol

Signed-off-by: Michael Ikey Doherty <michael.i.doherty@intel.com>
daemon: Finish implementation of delete_value

Signed-off-by: Michael Ikey Doherty <michael.i.doherty@intel.com>
util: Add utility to cleanup a BuxtonString automatically

Signed-off-by: Michael Ikey Doherty <michael.i.doherty@intel.com>
cli: Use name instead of key for consistency

Signed-off-by: William Douglas <william.douglas@intel.com>
shared: Don't set ret to true if get didn't show a value

Signed-off-by: William Douglas <william.douglas@intel.com>
shared: Fix error with checking element twice

Signed-off-by: William Douglas <william.douglas@intel.com>