Update SVG <symbols>

Now includes:
+ 'images/logos/github.svg',
+ 'images/icons/rss.svg',
+ 'images/logos/Google_plus.svg',
+ 'images/logos/Facebook.svg',
+ 'images/logos/twitter.svg',
+ 'images/logos/YouTube.svg',
+ 'images/logos/git.svg',
+ 'images/icons/issues-open.svg',
+ 'images/icons/envelope.svg',
+ 'images/icons/people.svg',
+ 'images/icons/info.svg',
+ 'images/icons/copyleft.svg',
+ 'images/logos/CreativeCommons.svg'
Load & use combined.svg

Load the combined SVG file the end of <body>
Update many icons/logos with <use> instead of inline SVG or <img>s
Set default-src to 'self'

By default, allow any resources from self
Applies to anything not covered by other directives
Use combined.svg as an external resource

Instead of using <use xlink:href="#id">, <use xlink:href="URL#id>
Added missing copyleft icon

Was using images/icons/copyleft.svg

Correct location is images/logos/copyleft.svg
CSS fixes for new SVG use icons

Start by settings dimensions. This resolves most issues.

Still need to fix transitions in Firefox.
Merge pull request #39 from shgysk8zer0/issues/38

Issues/38