Use local boost and compile tests only when required

[Rohit-Kakodkar]

CMAKE updates for faster compilation:

1) Use local boost directory when provided - Currently a version of boost is downloaded for every new compilation which increases compile times 2) Compile tests only when required - Only compile tests when BUILD_TESTS flags is ON

[sirpipat]

I will do it

[lsawade]

@sirpipat How about I do 1 and you do 2?

[sirpipat]

@lsawade It sounds like a good idea.