Use http instead of https for sourceforge badge

Author: mokun

index.html

@@ -571,7 +571,7 @@ <h3>B. Changes/Improvements in v3.07</h3>
 
 							<footer class="container" > 
 
-								<a href="https://sourceforge.net/p/mars-sim/" rel="nofollow"><img width="300px" src="https://sourceforge.net/sflogo.php?type=16&group_id=3286" alt="mars-sim at SourceForge" style="opacity:0.4;filter:alpha(opacity=40);"/></a>
+								<a href="https://sourceforge.net/p/mars-sim/" rel="nofollow"><img width="300px" src="http://sourceforge.net/sflogo.php?type=16&group_id=3286" alt="mars-sim at SourceForge" style="opacity:0.4;filter:alpha(opacity=40);"/></a>
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 								<a href="https://github.com/mars-sim/mars-sim/" rel="nofollow"><img width="300px" src="https://assets-cdn.github.com/images/modules/logos_page/GitHub-Mark.png" alt="mars-sim at GitHub" style="opacity:0.4;filter:alpha(opacity=40);"/></a>
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