Move platform selection logic to it's own script.
Fix cmake's ability to find hunspell on homebrew.
Merge pull request #30 from ahmedcharles/travis

Move platform selection logic to its own script.
Merge pull request #29 from ahmedcharles/cmake

Fix cmake's ability to find hunspell on homebrew.
Use the suffix -dev for development builds.

Users can change this locally if they wish.
Cleanup and explain TARGET difference for Mac.