Building JsonCpp with CMake

JSON is a plain-text data file format that has become popular because it is easy for humans to read and write, easy for machines to parse, and it is the standard data format used in JavaScript.

Open source JSON parsers are available for in a variety of languages; a popular library in C++ is JsonCpp.  In TubeTK, we want to use this standardized format more extensively to configure complex algorithms for reproducible analysis, etc.

Since TubeTK is primarily written in C++ and uses CMake for its build system, we created a CMake configuration for  JsonCpp.  This also makes the project easier to use as a CMake ExternalProject.  The newly created jsoncpp-cmake repository can be downloaded with Git: enjoy!