Set version to 1.5.1
Merge pull request #103 from ebi/1.5.1

Set version to 1.5.1
Ignore .DS_Store files
Remove unused images and losslessly compress the rest.

Also, add forkme_left_red.png in the repo and optimize it.
Add alt text and image dimensions for download-button.png.
Remove type="text/javascript".

This is no longer needed for HTML5.
Remove trailing spaces and extra newlines.
Include less.js after all the css files.
Use https for the Github links.
Remove the unused Twitter script.
Remove unit from zero.
templates/layout.rhtml: Minor html5 fixes.
Include html5shiv.js for older browsers.
Fix validation errors.