REST: Filter projects by 'linkname', not 'name'

REST: Filter projects by 'linkname', not 'name'

Based on a report on the OVS mailing list, it appears that projects are
being filtered on the 'Project.name' field instead of the
'Project.linkname' field. Correct this and add regression tests to
prevent it happening again.

Signed-off-by: Stephen Finucane <stephen@that.guru>
Fixes: 08b2115 ("REST: Allow filtering by both project ID and linkname")
Closes-bug: #117 ("Projects are filtered on the wrong field")
Cc: Daniel Axtens <dja@axtens.net>
[dja: drop mangling of value]
Signed-off-by: Daniel Axtens <dja@axtens.net>