[backport][7.1.1] RFR: JMC-6783: OPS4J Maven Repo no longer available

[Guru]

Hi,

Please review the fix (back port of https://bugs.openjdk.java.net/browse/JMC-6778 <https://bugs.openjdk.java.net/browse/JMC-6778> applicable to JMC 7.1.1 dev branch i.e http://hg.openjdk.java.net/jmc/jmc7 <http://hg.openjdk.java.net/jmc/jmc7>) 

JBS : https://bugs.openjdk.java.net/browse/JMC-6783 <https://bugs.openjdk.java.net/browse/JMC-6783> 
Web rev : http://cr.openjdk.java.net/~ghb/JMC-6778/webrev.0/ <http://cr.openjdk.java.net/~ghb/JMC-6778/webrev.0/> 

Thanks,
Guru