Updates for bower-specific folder changes and windows builds

I made some updates to build.coffee to point to bower-specific changes ([components -> bower_components](https://github.com/bower/bower/pull/435)). 

Also made changes to get the build to run under Windows:
1. Added `\r` to the `variable.about.replace` regex to handle windows-specific line endings. That character wasn't getting picked up and it would cause the validation step to hang on windows builds.
2. Put conditional in build.coffee to check for windows/non-windows to set the beginning of `dir` accordingly. I placed the variable `isWin` in the same location as the other variables to follow that file style and then used it in mkdir to initialize the `dir` variable. It covers [the case apollolux brought up on issue 240](https://github.com/alexgorbatchev/SyntaxHighlighter/issues/240#issuecomment-20236213). 

I also changed the javascript references in  tests to point to the new locations so that they would run. I wasn't sure if you were going to phase out qunit testing (and some of those files) -- that's what it looked like from previous changes -- but xregexp (for now, though I believe that changes in 3+) has a reference to qunit so I used it to make those work for the time being.

Last, I added a README.md in the build folder with updated build instructions.

Build now seems to be working for me on Bodhi 2.3 with node 0.8.25 (using node-sass 0.3.0) and node 0.10.12 (node-sass 0.5.0) as well as on Windows7 under node 0.10. These updates should cover problems brought up in [issue 240](https://github.com/alexgorbatchev/SyntaxHighlighter/issues/240)

Notes:
* I was originally going to add `node-sass` to the `devDependencies` but then found that the build wouldn't work under node 0.8. If I added `node-sass 0.3.x` instead, the build wouldn't work under node 0.10. So I left it out and just added that information to the build folder's README.md because I wasn't sure if you wanted to maintain support for node 0.8. 
* bower won't install anything on node versions pre-0.8. It will give a `TypeError: Object #<Object> has no method 'tmpDir'` because the `os` module [doesn't include `tmpDir` until 0.7.11](http://blog.nodejs.org/2012/06/15/version-0-7-11-unstable/)
* There are libraries available (like [mkdirp](https://npmjs.org/package/mkdirp)) that might be of use in handling the `mkdir` functionality in build.coffee. I didn't really want to start adding dependencies and making those changes without some discussion.