tracker: Correctly escape strings on sparql updates
tracker: Correctly escape strings on sparql updates

When creating a sparql query, only the special characters need to be
escaped. However, g_strescape replaces the non-ascii characters with a
'\' followed by their octal representation. This results in a invalid
query when a string contains non-ascii characters.

Using tracker_sparql_escape_string function instead of g_strescape
fixes this issue.

GNOME/grilo-plugins,GNOME/grilo-plugins