First attempt at a CMAKE build system

now we can build gamgee and run tests. It all works on CLION!!!!
Address @nsubtil comments on code-review

* move find packages to root CMakeLists.txt
* swtich add->definitions to target_compile_definitions
* add variant builder files to the project
make library static
Merge pull request #329 from broadinstitute/mc_cmake_clion

First attempt at a CMAKE build system