The install script now has a bash function available to prompt
the user for a y/n input to a question. This function can be
used instead of repeatedly reading into a throwaway variable and
then using an if/then/else/fi block.

All such instances were replaced with the new function.

Some prompts were reordered or edited for clarity.
Merge pull request #28 from ColoradoSchoolOfMines/install_improvements

Improve install script prompts.