Set Verbose g++ Output

- Set the flag for verbose output from g++. This should help us see why
travis builds are failing to include entity.h
Check CMake Version

- Let's see what version of CMake we're using.
Update to CMake 2.8.11

- This will allow us to use `target_include_directory`, which might help fix our build issues.
CMake Use target_include_directories()

- Maybe will help with build failures. Probably not.
Update CMakeLists.txt
Fix CMakeLists.txt

- There was a mistake in target_include_directories. This fixes it.
Build Cleanup

- Remove testing stuff that was added while attempting to fix the build.
- No longer building sdl2 from source to help speed up the build.
Typo Fix

- Made a typo, fixing the typo.
Update CMake for Builds

- Let's try updating to cmake 3.
More CMake Fixes

- Just shooting in the dark here.
Downgrade CMake for Builds

- The install of cmake 3 is poop and takes too long.
More CMake Fiddling

- Still trying to find a good CMake ppa.
Trying CMake 2.8.12 (Again)

- This ppa seems to be meant specifically for travis builds, so hopefully this on will work.
Try Removing Old Version of CMake
Merge pull request #79 from excaliburHisSheath/build_fix

Travis-CI Build Fix