[SCB-1297] NPE would be arised if you haven't set any value for servicecomb.config.ignoreResolveFailure

[HuaiJoe]

…vicecomb.config.ignoreResolveFailure

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[yhs0092]

#1292

[coveralls]

Coverage increased (+0.02%) to 85.755% when pulling 4660a20 on HuaiJoe:master into bc333c5 on apache:master.