removed submodule
Squashed 'externals/include/cppzmq/' content from commit ee47ae4

git-subtree-dir: externals/include/cppzmq
git-subtree-split: ee47ae4cddc304741526c9bb2035f98c3274e0ec
Merge commit '2254a0e5c6acb7204e45c94c13ffb47640ec9ec1' as 'externals/include/cppzmq'
added cppzmq as subtree