message: Update supported environment and add to README
diff: @@ -4,8 +4,8 @@ Third party contributions are essential for making SDL great. However, we do hav
  ## Environment
  Currently supported:
  -* Ubuntu Linux 14.04 with GCC 4.9.x
  * Ubuntu Linux 16.04 with GCC 5.4.x
  +* Ubuntu Linux 18.04 with GCC 7.3.x
  * [C++11 standard](https://github.com/smartdevicelink/sdl_evolution/issues/132)
  ### Issues
  