Minor code cleanup

__Changes__:
1. Remove the extension so you don't need to type it when running the script and so the script is less dependant on being written in bash/sh.
2. Use more heredocs instead of using echo for multiple lines of HTML.
3. Minor indent/whitespace changes.

Ignoring whitespace, the output of my version of the script should be the same as yours (given the same initial conditions). Feel free to use rebase/cherry-pick if you don't want all my changes.

__PS__: I'm not sure if you can count on being able to use scripting languages other than bash for compatibility reasons, but I thought it would be cool to experiment with porting your script to Ruby so I could use ERB for templating the HTML. I managed to get it to work, and I have branches for a Ruby version of the script and another version that replaces the script with an ERB file in [my fork](https://github.com/thenickperson/infohgen). Let me know if you have any suggestions.