Mac MakeFile and README

[mykeels]

• clean up mac makefile, so it works on new directory structure
• fix up README so it's easy to read
• modify mac installation section in README

[Thecarisma]

@mykeels kindly review the Makefile naming format. Delete your makefiles/mac folder and rename the Makefile to Makefile-Mac.mk and also build the make file in a way that it can build the simple binary without been moved from that folder so that new contributor can just execute the command on their machine and have the binary built in the simple/src/dist folder. So contributor can build the binary with the like of the command below
user@mac $ make -f Makefile-Mac.mk

[appcypher]

Since the issue has been fixed in another PR, I think this PR can be closed now.