Losslessly compress images.

Before: 464 KB (476.120 bytes)
After:  418 KB (428.799 bytes)
Merge pull request #209 from XhmikosR/images

Compress images
Update HTML files.

* Move meta charset first
* Remove unneeded default script type
* fix some validation errors from index.html
Trim trailing spaces.
index.html: use the relative link to 2.x pages.
2.x pages: tril trailing spaces and use html5shiv from bower_components.