Bug 925185 - Part 1: Add add_java_jar to moz.build. r=gps

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extra : rebase_source : 3e637b09ccf908b77ecd65f3b598796514d42eed
Bug 925185 - Part 2: Use add_java_jar and restrict JAVA_JAR_TARGETS to moz.build. r=gps

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extra : rebase_source : ce01a48bf13e3173dec631fa1f52cb3c9ad35e89