bugfix and documentation update

blueshift wasn't handling nighttime calculation properly, but I realized it
wasn't necessary to calculate nighttime. If it's not day, it's gotta be night.

I'm also checking for an active X Window session using $DISPLAY.
Updating documentation
More documentation edits
Provided installation instructions.
Implemented and tested v1 of blueshift.
Documented tool in README file. Now to implement it accordingly.
Initial commit. Using 2-Clause BSD license.