Removed ParserItemTemplate.hpp for install list
Removed CJSON check to top level CMakeLists.txt file
Changed include path to cJSON
Added function install_headers() which will retain header prefix path
Moved enable_language( C ) to top level CMakeLists.txt
Merge branch 'master' into cmake-package-config
Changed Findcjson.cmake to use OPM_PARSER_ROOT as prefix - if CJSON_ROOT has not been set
Added install-headers function + opm-parser-prereqs.cmake
Merge pull request #36 from joakim-hove/cmake-package-config

Cmake package config