Old version cmake build fails

[Hemraj Kerkar]

reference #40
I tried building the project in cmake 3.2.2 but gives errors like

• cannot run .c
• threads not found
  but when i upgraded to cmake 3.8.2, the build was successfull
  so right now i'm using gcc - 7.1.0 & boost - 1.61

it will better to provide the least version of cmake supported, for those who are new to this repo.

Regards.

[Vlad Lysyy]

@reoxey - many thanks for root causing it, I have updated the top level CMakeLists.txt with correct minimum version spec -> 7141606