Merge pull request #24 from sunnycomes/dev

LGTM.
Add disqus.snippet which is the code snippet for disqus comment box.

Add github_fork.snippet which is the code snippet for github fork bar.

Add google_analytics.snippet which is the code snippet for google analytics service.
Add function get_3rd_party_snippet in module settings.
pass 3rd party code snippets to templates as params.
Move github fork bar code snippet to footer.html.
Replace google_analytics.html with google_analytics.snippet.
Replace disqus.html with disqus.snippet in all template files.
Remove unused files.
add '{%autoescape None%}' for footer.html.
Change github_link-->github_fork_link.
Merge branch 'master' of https://github.com/sunnycomes/IoVision into sunnycomes