[tracker] (8 commits) ...Merge branch 'wip/carlosg/joining-services' into 'master'

[Sam Thursfield <sthursfield src gnome org>]

Summary of changes:

  154ef78... libtracker-sparql-backend: Fix tracker_sparql_connection_ne (*)
  1e51a9f... libtracker-data: Interpret bindings from a service table as (*)
  9c6ca6e... libtracker-data: Check binding type before printing variabl (*)
  14392fd... libtracker-sparql: Join services table queries on the right (*)
  c50f767... libtracker-data: Avoid repeated variables in remote service (*)
  193b848... tests: Add libtracker-data test to test SERVICE queries (*)
  bfd8c37... libtracker-data: Fix column check in services virtual table (*)
  5e6c25d... Merge branch 'wip/carlosg/joining-services' into 'master'

(*) This commit already existed in another branch; no separate mail sent