Fix compilation problems in Fedora 19

These two commits fix the compilation problems I have in Fedora 19, issues https://github.com/Grive/grive/issues/186 and https://github.com/Grive/grive/issues/187
 + The json-c library has changed its path in 0.11, see: https://lists.fedoraproject.org/pipermail/devel/2013-May/182258.html
 + bgrive tries to install a non-existent grive.1 man page