Use https for Eclipse maven repo.

Fixes #402

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=277798821

Author: eaftan

eclipse_plugin/pom.xml

@@ -40,7 +40,7 @@
     <repository>
       <id>mars</id>
       <layout>p2</layout>
-      <url>http://download.eclipse.org/releases/mars</url>
+      <url>https://download.eclipse.org/releases/mars</url>
     </repository>
   </repositories>